Lineage and Graphene are based on android and bear the danger of support loss when google drops support.

PostmarketOS is actual Linux (alpine is the base to be exact).

Graphene definitely is a lot more advanced since it uses all the proprietary blobs of android. There is no use in comparing the two. Its like comparing lemmy and reddit in terms of technical finesse.

It works very well for some apps already but it is highly dependent on people supporting either financially or through contributions (code, issues, translations, documentation, tutorials).