How is simplex going to turn a profit for the people who've currently invested in it? This is why things get enshittified, they have vulture capitalists helping them start out and no one thinks about it till one day it comes time to pay the piper and features start getting broken, ads get shoveled in, and unless enough money is generated the app will eventually fail.
I hope simplex finds a way to go non profit, until then I can't trust their business model to not shift in the future.
The software from Unminable is Windows only but you can mine on them with any other Linux based mining software.
Monero isn't directly mined with GPU but if you look under "coins" section on moneroocean you can mine other algorithms and get paid in XMR using them.