The ghost mech factory, boss fights and the desert which spawns a bunch
make sure to only build roads after you connect the area, because it costs a lot more for non connected areas
Miyoo Mini Plus if you can get your hands on one, try a local electronics/gaming market.
I think if you can just get a Switch Lite (pre-owned) can't go wrong with it and if you get NSO + then you get access to tons of retro games.