A couple of last years were quite impressive in how mobile linux improved.

Still, people claim: - open-source phones are low-end devices - but we (also) write our DTS for phones like Xiaomi, Samsung, OnePlus, etc. Personally, I've written dts for my Xiaomi 12 lite and packaged postmarketOS for it. for devices like Fairphone - there's already a good level of support in mainline - mobile linux is slow and laggy - this comes from the 1st point. modern smartphones works quite smooth, and mine xiaomi phone running on sm7250 (mid level soc from qcom) feels very snappy. hell, even desktop browsers works quite good on more or less modern phones (chromium is especially smooth) - UI is trash - please check out gnome-mobile. it's an impressive piece of work and feels very much like modern mobile UIs - my bank/government/etc forces me to use ios/android app - we have waydroid! so, you can run any android app from your launcher (which will be running inside a container with lineageos). the integration might not be super complete right now, although it closes the gap for me.

Of course, there are many gaps (like camera works on very few devices and photo/video quality cannot be compared to android; some apps are still not adaptive) but many enthusiasts continue to improve on all the directions. Kudos to all of them! Personally, I wait for VoLTE and immutable systemd-based pmOS.