I think you are looking at this from a different angle than me. PostmarketOS is a small project which is very dependent on community contributions. The fairphone 4 is community supported and this means it works pretty well. See wiki for more info: https://wiki.postmarketos.org/wiki/Devices

Most people who come from the proprietary „give money, get product“ world think only official support counts and they will get anything more than community support which is not the case. In the open source world, if you dont have the skills to repair your device, you ask someone to help and often they do for free. If you need it done NOW, you pay someone for it. Its not different than in proprietary land. Fast, good, cheap. Pick two! ;)