Switch needs folders so bad. My ACA collection is already out of hand.
Anyway, classic publishers/libraries Hamster has licensed or owns access too:
Data East (G-mode)
Escape/WestOne (Lat)
Irem
Jaleco (Clarice Games)
Konami (plus Hudson)
Nichibutsu (Hamster owned)
Nintendo (Switch exclusive)
NMK (Hamster owned)
SNK
Sunsoft
Taito (Square Enix)
Technos (Arc System Works)
Tekhan/Tecmo (Koei Tecmo Games)
UPL (Asya)
Video System
People asking for Capcom, Namco (plus Banpresto) and Sega (plus Sammy and Atlus) games should just stop now too. They won't bother as they'll want to do their retro services and collections. I suspect Cave and Eighting fall in this camp too, or just prefer working with M2 on premium older stuff. Zerodiv has Psikyo covered already too.
There are other classics Hamster could get though. Personally I'd like to see Toaplan (whoever owns it), Mitchell, Kaneko, Seta (Aruze), Visco, Seibu Kaihatsu (Moss) and the other Data East games (owned by Paon).