I have the Miyoo not the RG35XX but my understanding is they are very comparable and only have a few differences - you will enjoy it. Handheld emulators are ace
I use my Miyoo Mini every night
Standard advice when anyone gets one of these devices though - ditch the SD cards it comes with. Literally snap them in two and use your own SanDisk or Samsung or reputable brand. The off brand SD cards will randomly die without fail after a few weeks.
Get Garlic OS as it's miles better than stock firmware and easy to setup:
https://www.patreon.com/posts/garlicos-for-76561333Either use your own ROMs or google the phrase "Tiny Best Set Go" and see where that takes you (curated games list).
Only big difference between Miyoo and RG35XX is the Miyoo Mini+ has wifi which really is only good for retro achievements so you aren't missing too much. RG35XX has a built in clock which is needed for pokemon (miyoo can sync time on wifi though so much and such the same).