O2P Max (finally)

After multiple orders (AE, Ayn,..) i lost my patience and i went all out to grab a local O2P max for €400. Great deal imo since its not to old & also comes including all accesories.

Now i followed a Retro Handheld Corps startup guide from his OG Odin 2, but didnt have enough time yet for all steps (ended at Retroarch)

I'll probably go for buying DE-ES once trough patreon and then i'll get to keep it, right?

Also, wich others paid purchases are recommended?

I plan on playing GBA, GBC, GB, Switch, Wii, Gamecube, 3DS, PS1 & PS2.

I prefer one time purchases on not monthly purchases.

Also wich other to do's for a new device? thanks in advance!