We can divide this verse into (i) a faith statement and (ii) a historical statement.
Reading the verse in this interlinear with morphology, we see the verb προσφέρω first being used in the perfect tense, in the faith statement, then later on in the imperfect tense in the historical statement.
This Greek verb tense usage; hence, verb aspect usage, seems to present (i) the kind of faith at work in Abraham, as well as (ii) the kind of attitude that came out from that faith—one sentence talks about the faith, and the next about the works prompted by that (living) faith.
Presentation (i) is the faith statement with προσφέρω in the perfect tense, προσενήνοχεν, which presents Isaac in a state of having been offered, which resulted from a completed action of offering—Abraham absolutely determined in his heart to offer his promised son, and regarding him as a fully consummated offer. This very inspired Hebrews text reveals us the point of view of Him who reads the hearts and sees faith: Isaac had been actually offered.
Presentation (ii) completes the scene revealing us that Abraham did not back down from his faithful obedience of offering up his son. During the length of time it took for the offering preparations, from the beginning until the last moment, when the angel held Abraham's hand, the whole time Abraham was offering up his son—the continued, not completed kind of action communicated by the imperfect Greek tense, προσέφερεν.
Now, as far as translations go, while the KJV renders προσενήνοχεν and προσέφερεν the same, "offered up", not all translations do that. The CLNT, for instance, brings:
By faith Abraham, when undergoing trial, has offered Isaac, and he who
receives the promises offered the only-begotten, (Heb.11:17, CLNT)
Not quite there as the interlinear with full morphology, especially in the historical statement, but at least distinguishing between the two forms.