Maybe consider Nura (formerly known as postmarketOS) over Sailfish. Sailfish has a proprietary userspace, and I’m fairly sure they rely on an Android kernel, meaning once the LTS kernel stops being supported, it will no longer be updated.

Meanwhile, Nura uses mainline or close to mainline kernels, much like Linux desktop computers, and the DEs are fully open source. I personally like GNOME Mobile the best with Plasma Mobile coming in second (Plasma Mobile basically being a clone of the Android UI). The Fairphone 5 is close to being feature complete, and if you don’t mind using AI-assisted code, the Fairphone 6 and 6+ is even closer to being feature complete when using TheMightyCat’s build of Nura (Nura doesn’t allow LLM code in their repos, so the userspace tools and the non-mainlined kernel code cannot be included in the Nura repos and are kept in separate repos).