"As for your "SRB2 into Adventure" list, you could include MIDIGuy's Final Demo Adventure Mode port? It makes it so that you can just walk into monitors to break them"
I think a suggestion I feel is valid is the Modern Monitors mod, which I think is somewhere in the Assets category? This mainly covers that one bit of what klasky suggested though.By the way, I recently released an SA2-styled explosions mod to go with SA-Sonic. Expect me to compile a list of recommended mods for those who want to transform the whole game into Sonic Adventure! Let me know of any mods I should know of just incase!
It modernizes the monitors to look pretty much how they began looking in the Adventure games and onward, you can even walk through them I think.
There's also the Checkpoint Rewards mod that grants you random rewards, which I think was a feature in the Dreamcast era, was it?
Also, I don't believe I've vocalized this in a long time here, but man, SA-Sonic is looking to be one of the best mods to play with! I hope I have just as much fun trying him out as with the .gifs showcasing his gameplay.