What follows is an analysis taken from a technical commentary by John Goldingay who provides his own translation directly from the Hebrew: Baker Commentary on the Old Testament Wisdom and Psalms: Psalms 1-41.
I think the reason why different translations don't agree with the pronoun assignments, or leave the pronoun purposely ambigious, is because the Hebrew itself is inherently ambiguous. So your question is definitely legitimate. But Goldingay leans toward interpreting God delighting in the faithful's way, although not conclusively. Psalm 37 is an alphabetic psalm, so verses 21-22 start with Hebrew consonant 'l', 23-24 with 'm', and 25-26 with 'n'.
Here's his translation for verses 21-26:
21 The faithless person borrows and cannot repay,
but the faithful is gracious and gives,
22 For the people blessed by him/who bless him take possession of the land,
but the people belittled by him/who belittle him are cut off.
23 By Yhwh a man’s steps have been made firm
when he delights in his way.
24 If he falls, he is not hurled headlong,
because Yhwh upholds [him with] his hand.
25 I have been young and now I am old,
but I have not seen a faithful person abandoned
or his offspring seeking bread.
26 Every day he is gracious and lends,
and his offspring are a blessing.
Here's Goldingay's commentary on verses 21-22:
The l lines introduce the topic of borrowing (lāwâ), which is also related because the bad times are the times when people have to borrow. I take the faithless person’s defaulting on a debt not as a sign of wickedness but rather as a further sign of receiving the due reward for faithlessness, because the defaulting will threaten harsh consequences (see 2 Kings 4:1; Neh. 5; Amos 2:6–7). Faithless people will never be able to get out of the poverty trap. The second colon then offers the contrast that the faithful will be in a position to be gracious and generous -— in lending (cf. v. 26) and even in giving what one does not expect to be paid back.
The companion line explains the difference between these two destinies in the familiar terms. The “him” is presumably Yhwh, who is the one who blesses and belittles or is blessed and belittled; the word for belittle (qālal) is less fierce than the more technical word for cursing (ʾārar). Blessing is a word that results in an event; in the case of the opposite verbs, cursing refers more to the powerful word, belittling more to its aim or result. The act of blessing adds to people, making them prosperous and fertile; the act of cursing cuts them down, making them unsuccessful and unproductive. Thus the result of blessing and belittling/cursing is the usual antithesis, ability to enjoy ongoing possession of the land or being cut off from it.
And here's his commentary on verses 23-24:
The m lines lead to an opening that refers to Yhwh (myhwh, “from Yhwh”) but goes on to another m word, a rare word for steps (miṣʿădê). Yhwh enables people to keep a firm footing, because of “delighting” in them (ḥāpēṣ). In other contexts such delight might issue simply from God’s grace, but in the context of this homily, it is likely that the people Yhwh delights in are the faithful, mentioned (for instance) in the l and n lines on either side. This point would be explicit if the colon refers to the man’s delighting in Yhwh’s way, but the pronouns are again ambiguous.
The image of steps continues in v. 24, the two lines being parallel, aba′b′. The homily is not wildly unrealistic. It recognizes that the faithful do fall; to make sense in the context, EVV have “stumble,” but the word is nāpal, the regular verb for “fall.” But the faithful do not fall in such a way that they fail to get up again, or they do not get hurled out of the land (cf. this verb, ṭûl, in Jer. 16:13; 22:26, 28). How is that? The second colon explains; “upholds” (the participle sōmēk) recurs from v. 17. Yhwh takes the hand of people who fall and lifts them up, or gives them a hand, supports them with a hand.
Finaly, here's his commentary on verses 25-26:
The n lines are distinctive for comprising a tricolon as well as a bicolon and for making an assertion that often outrages Christians. The n word is “young man” (naʿar); in the first colon the preacher claims a lifetime’s experience on the basis of which to make the pronouncements in the second and third cola. Since the preacher has just referred to the fact that the faithful do fall, we should perhaps take the statement as hyperbole. It then still makes a declaration for the faithful to hold on to when Yhwh does abandon them for a while (see 22:1 [2]). If we read it in the context of that preceding recognition that Yhwh does let people fall but does not let them be finally thrown out of the land, this would fit the final colon’s reference to their offspring begging for food. The statement is another formulation of the promise that the weak will enter into possession of the land. They will therefore be in a position to feed their offspring and pass it on to them so that they continue to eat.
Verse 26 then puts the point positively. The faithful not only have enough for themselves and their families but are in a position to be gracious (cf. v. 21) and to lend (the hiphil of lāwâ “borrow” —- cf. v. 21). Lending properly involves simply lending—the Torah forbade making money through lending (e.g., Exod. 22:25 [24]). It is not a form of investment (see on 15:5). Lending might seem less generous than giving, though it might also offer more recognition of the other person’s humanity. Instead of making others the recipients of charity, lending gives them the opportunity to reestablish themselves and hold their head high. Yhwh’s support of the faithful enables them to play that role in the community. Like the negative point in v. 25, this blessing extends beyond one faithful person to the next generation. Because it inherits the land that Yhwh has enabled the faithful person to possess, it is also in a position to be a blessing, to be a means of the blessing of food coming to other needy people.
A dynamic (but faithful) NLT translation agrees with the pronoun assignments, translating Ps 37:21-26 (l, m, n) this way:
21 The wicked borrow and never repay,
but the godly are generous givers.
22 Those the Lord blesses will possess the land,
but those he curses will die.
23 The Lord directs the steps of the godly.
He delights in every detail of their lives.
24 Though they stumble, they will never fall,
for the Lord holds them by the hand.
25 Once I was young, and now I am old.
Yet I have never seen the godly abandoned
or their children begging for bread.
26 The godly always give generous loans to others,
and their children are a blessing.
