Does postmarketOS use android-based binary blobs, and what does it have over such projects as Google-Free LineageOS (as in, if you don't flash opengapps) or Replicant?
The biggest difference is, that Android's build system is completely avoided as of now. The system consists of small packages, and you can easily modify those parts without rebuilding the entire system.
Regarding blobs, right now there are no blobs running in the userspace. Firmware blobs are needed for Wifi for example. There are plans to both allow proprietary blobs in userspace (to get accelerated graphics for people who want that trade-off), but at the same time to make these entirely optional.
Relevant part of the post[0]:
"In contrary to most Linux on smartphone projects, almost all these photos and the video are taken off devices which do not run proprietary code on the main CPU. The only exception is the Droid 4, which @NotKit owns. He is actively working on making proprietary Android drivers usable in postmarketOS with libhybris. Libhybris allows devices lacking FLOSS drivers to make full use of their hardware."
"While we don't welcome binary blobs and prefer to sandbox them where we ship them at all, we embrace this solution for people who want it. However we intend to keep closed source components entirely optional, so you can run pmOS as libre as you want it."
For most devices, we're running the vendor forks of the Linux kernel (mostly Android). The source of all of them is available, just like the mainline Linux kernel.
With that being said, the stock Linux kernel and its vendor forks contain obfuscated code and even (small) blobs. To get rid of that we would need to package something like the Linux-libre patchset [0]. From what I know, no one is planning this currently, but if someone is interested in this, I don't think anyone in the community would be against having this as option.
