I see there are a few issues when launching the Linux version of the game (what a surprise...). I'm going to leave mine here, since the solutions proposed in other threads have not solved my problem. When launching start.sh from a terminal, this is what I get:

Running Momodora: Reverie Under the Moonlight
GameFiles/MomodoraRUtM: /home/michaelpalin/Games/Momodora Reverie Under the Moonlight/game/GameFiles/runtime/i386/lib/i386-linux-gnu/libgcc_s.so.1: version `GCC_7.0.0' not found (required by /usr/lib/i386-linux-gnu/libstdc++.so.6)

Not very hopeful about this one, but any response will be appreciated. Will likely end up wine-ing the Windows version, disappointed emoji.

I had this solved by editing the following file:
/path/to/GOG Games/Momodora Reverie Under the Moonlight/game/MomodoraRUtM.sh

search the line
export LD_PRELOAD='/usr/$LIB/libstdc++.so.6'

and put a "#" in front (uncomment)
#export LD_PRELOAD='/usr/$LIB/libstdc++.so.6'

I still had more issues, but reported my solutions on them in another tread.
Using Fedora35 on an Nvidia Optimus Setup.