Revision 2021

One MSX2 release in the oldskool demo section
CaT ArT SyS by ThePetsMode

You can use whatever you like, it's all up to you.
Certain competitions may have harder restrictions or put demos in different categories depending on expansions but the oldskool category on Revision would certainly allow FM-PAC / SCC.

I can't say whatever motivation others have for choosing to not use expansions but one consideration is that it limits the amount of people able to watch the production on real hardware, this could matter if you do things with the hardware that emulators have problems with.

So I understand that Revision got banned from Twitch?

Forest Nymph probably and/or 08082020 - Gazing into the Abyss
:o

Note that there are 2 streams (the original (as Meits linked) and hq/passthrough): https://streaming.media.ccc.de/revision/

(Official) timetable has been updated. Says 22:40 now + re-run of PC 64K added. What you see under the video is most probably outdated / still the original schedule. (Or you could be looking at Saturday, not Sunday perhaps? )

Anyway, should be fun