Yo! Dumb pedantic user here, and I really do agree that most freeware VSTs sound like utter arse, so I can pretty much only recommend (I say recommend with a hint of caution) these few:
Drums: Mt PowerKit
https://www.audiopluginsforfree.com/mt-power-drum-kit-2/
It's free but I think the drum's tonality is tailored more for rock/metal than the general pop style your music has.
Guitars: Ample Sound Plugins
https://www.amplesound.net/en/index.asp
Some of their plugins are free, BUT in my honest opinion, also sound like arse because for now, I don't think guitar emulation technology is good enough to sound like the real thing. But given the fact that they're free, who's to complain?
Piano: ???
http://www.vst4free.com/index.php?plug-ins=Piano/Strings
I don't really have much experience with piano VSTs, it's not really my area of expertise, so I can't recommend anything here.
But, (excuse this horrible attempt at humour) for a limited time only, I can offer live recordings for the acoustic guitars for free! This is of course, with the conditions that you:
1) Stay healthy
2) Keep up the good work!
Cheers!
P.S. Is there any way to contact you directly regarding other pedantic "issues" about the musical composition?