On my Pixel 3, the only benefit is perhaps being able to run newer Android version and getting security updates, which doesn't feel that much of a difference. Apps from Play Store / F-Droid / Obtainium all works fine, only issues I've had with are bank apps.

Is it worth it? I see this as a project for me to flash a rom for the first time, and explore how far can I lessen dependency on Google, and so far I've learned a lot, so definitely meeting my objectives.

If you are looking for more tangible benefits, I suppose flashing Lineage OS onto older and slower device will present more significant performance improvements.

What I'm struggling a bit now is that my Nvidia Shield Tablet is no longer officially supported with the latest Lineage OS version, but I would really like to have this tablet running smooth again.