I bought a Xiaomi A3 about four years ago. I’m still using it now but my experience has been mixed.
Two years in, my carrier told me I had to switch phones because it didn’t support a bunch of technology they now require. It in fact supported everything including all the correct GSM bands, but ATT was now operating on a whitelist to which my phone did not belong, and they would not produce an explanation as to why. I was able to switch to T-Mobile at a reduced rate, but I find the coverage leaves much to be desired by comparison.