To date the Retroid Pocket 2 is still the best sub $100 retro handheld at $80. I'm still using a wide range of gaming options personally but the RP2 gets used more than anything else.
I'm curious how long it will be before the Retroid Pocket 3 comes out. With how rapid things are developing in this arena it could definitely happen this year.
https://www.goretroid.com/products/retroid-pocket-2-handheld-retro-gaming-system
Photo by Me (Samsung Note 10 Plus Camera)