(I must preface this by saying, just because a psalm is poetic, it does not therefore take away from the fact that it is also making a truth statement, and accurate. Jesus quoted psalm 82 about the gods and said it was written in the Law John 10:34 and the educated class did not turn around and counter saying that’s conjecture and hyperbole)
“he makes his messengers winds, his ministers a flaming fire.” Psalm 104:4
The order of the words, the syntax indicates in my mind that messengers are precursors or procede their future state as “winds”
ο ποιων τους αγγελους αυτου πνευματα και τους λειτουργους αυτου πυρος φλογα (LXX)
The English ESV translates the Hebrew as being winds, the Greek LXX as pneuma or spirit and even when this passage is quoted in the NT some English translation switch from winds to spirits
“Of the angels he says, “He makes his angels winds(spirits), and his ministers a flame of fire.”” Hebrews 1:7
Whether they are winds or spirits is not the question. The question is whether the aggelos/angel(s) are already spirits (non-physical) or whether they can be made into spirits, take the form of spirits? And by extension were NOT in their initial state spirits, meaning they were physical, even if it’s a superior form of physicality which we would refer to as supernatural.
One verse that might indicate all angels are spirits and which would have to be asked as a separate question on its own, as to the syntax of the verse is
“Are they not all ministering spirits sent out to serve for the sake of those who are to inherit salvation?” Hebrews 1:14
Are all angels ministering spirits... sent out? Or are only the ministering spirits sent out? Do all angels serve those who are to inherit salvation? It seems unlikely that all angels have this one purpose in common
Bible says earthly bodies differ from heavenly bodies but the heavenly bodies are bodies nonetheless.
“There are heavenly bodies and earthly bodies” 1 Corinthians 15:40
Also spiritual does not equal spirit. A spiritual body is not a spirit, it can take on spirit qualities but it’s not limited to these
The children of Israel all are manna and that was physical food from a physical heaven but it’s referred to as spiritual food even though it has physical properties.
“and all ate the same spiritual food,” 1 Corinthians 10:3
Back to the original question
Does this passage in psalm 104:4 indicate that God makes messengers out of winds/spirits or winds/spirits out of messengers? Consider also the second part of the verse seems to read plainly in English that the ministers (plural) become a flaming fire (singular).