Any privacy oriented custom ROM doesn’t support my device (Redmi Note 13 4G) officially. e.g: calyxOS, LeneageOS, etc. But in telegram channel I got unofficial leneageOS and some other AOSP based rom. My question is that, can I trust this unofficial builds for my phone since I don’t know about the developer of these unofficial ports. And should I use these unofficial ROMs or stick to the stock ROM for now?
No, you most definitely can not trust these.
They are neither privacy nor security-oriented. Let alone unofficial builds.
No, you can hardly trust OSS software from unknown developers sometimes—let alone the OS itself.
It’s better to minimize smartphone usage (apps, surfing) on a non-updated phone and save for a new phone. If you can’t buy a new phone every few years, then get a mid-range Samsung or Pixel that has longer updates. Samsung already shut down the custom ROM route, disallowing bootloader unlocking. Custom ROM support on future Pixels is uncertain.
This is a horrifying sentence.
Please, please do not use these roms and stop downloading random software packages from the sketchiest of sketchy sources.