Xiaomi is the essence of Chinaware: Xiaomi are hard to open/repair (environmental unfriendly), workers don't get a fair wage, materials are not fairly resourced, it has a locked bootloader, they have their own bloatware (MIUI), probably contain spyware, and likely don't even pay fair taxes.
Also, the successor of Fairphone 4, Fairphone 5, has 5G and OLED.
e.g. Xiaomi Redmi Note 13 has an OLED screen and supports 5G SA for 140 EUR