I wonder why there is so many people scared about these kind of consoles. Not every portable should come from known and famous brands.
The issue is not the device but the site trying to sell it. I own a R36H and a R36S and I assure you both consoles are worth their price. One costed me 26€ and the other 20€, there is nothing as powerful as those for the price. If you don't care about tags and don't want to pay extra just for having a "premium" device which at the end has issues like any other, I would defenitely go for one of these. R36S is GameBoy style and R36H is horizontal style.
Both consoles have exactly the same SoC and the same screen panel (which is surprisingly good for the price), although the R36S has different revisions, but that's not an issue at all.
With them you can play up to PS1, most of N64 games and a few Dreamcast games not very demanding. From GBA going down, everything works perfectly. I use ArkOS and 0 issues. I am not a fan of portable consoles, but when I feel like playing one, these are my ones to go. I used the SF2000 before, and it was really nice, but it struggles with many SNES and GBA games not so easy to emulate, because it's a very basic device without any custom firmware.
I only buy retro consoles that cost 30€ or less, that's my rule and it will remain forever. Being said that, you can get things like these and enjoy tons of games.
So, my recommendation, if you want something cheap, functional and don't care about brands, get one right away, but take care because there are clones here and there.