Lindroid

>you can just use postmarketOS

Only if your device is fully supported

I have about 5 "post market" devices and only two of them have any support in postmarketOS: Redmi 4x, in which hardware acceleration does not work and I have not been able to run any DE on it and Pixel 4a, in which judging by the pmOS wiki page works just about everything except the most important part of a modern phone - touchscreen

postmarketOS provides tooling, documentation and a helpful community ... at some point, you'll need to put in the work, or sell your used devices and buy other, better supported used devices to work around this.

Is it really unfortunate that there's no (known) mainline/close to mainline touchscreen driver for the Pixel 4a? Absolutely. But it won't magically appear without somebody putting in the necessary effort.