The best way to experience #LinuxMobile is IMHO on former Android Devices like the OnePlus 6 or Pixel 3a, as these are well designed devices with SoCs intended for phones. While having native hardware would be great, it's really hard to produce relatively bug-free hardware from scratch. With mainline, the SoC is always going to be older, and small-scale production leads to high prices. The economics just don't work out for non-enthusiasts who then ideally are also up for paying a software support subscription. Also, as a manufacturer you'll want to somewhat control the experience, leading to 'yet another small scale device-specific distribution, which has it's downsides.
Across devices audio issues are unfortunately still somewhat common, in part caused by the Pipewire transition (things that had been figured out for PulseAudio need to be figured out again). But it's on people's radar, and funds are invested to solve this [2].
VoLTE is another challenge, as it allows to carriers to become more gatekeepy with their stupid device support lists - of course there are workarounds like using a SIP account, but that's too inconvenient for many. Also, RCS support is not yet there, but as long as SMS/MMS fallbacks are still around, this not a dealbreaker.
[0]: https://linmob.net, https://linuxphoneapps.org
[1]: https://wiki.postmarketos.org/wiki/Android_Translation_Layer
[2]: https://postmarketos.org/blog/2025/08/17/callaudiod-wireplum...