He-yoo, since Touhou 20 is coming out in like... right now and Reitaisai is like... right now
Quite a lot of folks are releasing their stuff, most of it is behind pay wall currently, but as for as available now:
Memento of a Red-White
Youtube XFD:
https://youtu.be/pFlGY7f7THM?si=4jE2QCSCndO26E9IBandcamp:
https://hazamayuutou.bandcamp.com/album/memento-of-a-red-whiteCheeky download linkDespite offering it for listen on bandcamp, definitely do consider the full purchase to support the artist. Even tho it just seems like arrangements of PC98 tracks in modern style, I'd argue each and every single of them are updates and also get creative with mixing in other songs like with Shrine of Hakurei mixing in Maiden's Cappricio or MS Final Stage actually incorporating heartbeats from Fires of Hokkai.
Furthermore, even though I am not always a fan of C&D, they did release
a pretty solid OST prediction of TH20 Fossilized Wonders trialYoutube video link:
https://youtu.be/k6B_T7mU5T0?si=Iv7pkLc4yUR79BLwSeparated into mp3s all tracks (altho first track has SFXs)Again, much like last time, when said circle
doesn't break ZUN's guidelines (they didn't originally add disclaimers to Fake Touhou 19 OST), get into dramas or make abominations beyond my comprehension, they do make some good predictions
And lastly to any of Marine Benefit fans and Kuroha fans.
I might be late, but there's one person who decided to remake entire MB OST
Either on YT:
https://www.youtube.com/playlist?list=PLGWLgebhd_YWhMJWoLCA4scHUyJjCrGvOOr arranger's website:
https://chrisoft.org/libs/music/playerAnyways onto things that will become available after Reitaisai, possibly
Unreal Exposition
https://irodorian.booth.pm/items/6857126Hifuu-style album produced or at least sold from... Pesot.jp? I'm intrigued.
It's physical only.

Yorin extremely quickly released an album I've missed and then, already, a second one!

The Incomprehensible Dreams of Girls:
https://yorindoshin.booth.pm/items/6627685Phantasmagoric Japaneze History:
https://yorindoshin.booth.pm/items/6795821Otobake / カタルシス少年戯樂団 has another two albums demaking both PCB OST:
https://youtu.be/xatiKta4xuwand PoFV OST:
https://youtu.be/NzoncRV82aE?si=jhUQ1Cjo8IPhn0m6in style of PC98, with some arrangements also being remixes, taking inspirations from different songs too!
Eban releases an album full of arrangements! Simply called
"If the Past Final Bosses Joined UDoALG"
XFD:
https://youtu.be/A8VO0lgV8fU?si=04FF_z1gtqe4qJalBooth:
https://eban.booth.pm/items/6812430It's exactly what you think it is, although limited to Windows era
Also do check out his TH20 Prediction song,
it's absolutely mesmerizing.Score of Imperishable Night
Myaga releases an album which you can purchase here:
https://omyaga.booth.pm/items/6855712XFD:
https://www.youtube.com/watch?v=1SN_HYArZocTrickster's SerenadeSisyou (most well known for organizing Garden of Sinners album) has released an album centered around Mamizou! (also features one song from DO) Some of the songs in it have already been posted on the channel, being remixes with Futatsaiwa with other character themes!
XFD:
https://youtu.be/QTdNWPc0gm4?si=Qs4MV7QCiG56izq5Will probably be sold on the event itself.
Aversante Magno Arbor SapientaeKomaInu releases another album in style of EoSD/DiPP era!
https://youtu.be/lc45rbsV6P8?si=RIT-fek-QAvtsI6-Mixture of Nature and Daydream
Album by HEL. Or Prism? Correct me either way!
So that's all from me, hope the music in TH20 trial is good too! Bye-o