http://sonic.sega.jp/SonicChannel/topics/sound/20180117_001527/

https://itunes.apple.com/jp/album/id1333859431&app=itunes

https://itunes.apple.com/gb/album/sonic-mania-original-soundtrack-selected-edition/1333856904

So apparently, there's a official Sonic Mania soundtrack that has more tracks than the official vinyl. It's almost considered the official complete soundtrack (almost because the tracks for Green Hill, Chemical Plant, and Oil Ocean don't appear to be listed on this soundtrack).

iTunes USA (https://apple.co/2B7XuhE)
Amazon USA (http://a.co/06ft3AM)
Google Play USA (https://goo.gl/azMUwG)

Well. This release is not lossless, and it's still missing tracks from the game, but it has more than the official digital release. I'm not sure why the Amazon set is the most expensive of the three, but the iTunes version will have the best quality.

Thanks for the US sources. Maybe the Sonic 1 & 2 remixes aren't there because of copyright stuff involving Masato Nakamura? Or maybe they're saving them for a potential complete release in the future? Anyway, this is the best official version of the Sonic Mania soundtrack we're going to get so far. If you want a more complete soundtrack, !!!!! has you covered (Thread 218908).

hoping for someone to upload it :D

Here you go:
Thread 222190

Here you go:
Thread 222190

Thank you for your contribution!