I have an R36S for about a year now. The software and updates have improved it significantly and I love playing retro games on it.
It has a Gameboy aesthetic and plays everything through the PS1 without a hitch - it is phenomenal for GBA, SNES, NES, MAME, and Gameboy stuff.
I have futz with the d-pad a bit to loosen it - very easy to do, but the standout on this is the screen. It is absolutely beautiful for a $35 handheld.
I play older games on this that I could on my switch as it just feels like a more genuine experience - just finished the amazing Metroid Zero Mission and I'm halfway through Link to the Past.
These cheap handhelds have gotten so good in the last few years, and they are so cheap, they are perfect for travel.