This is one of my strikes against the Punkt mp02: it doesn't work with most of my carrier options. I was hoping that either that device's capabilities would be extended, or its replacement would follow a similar ethic and expand bandwidth / protocols, but neither occurred. Further reading on Punkt's offerings has further cooled my interest (bugs, fragile HW, spendy).
RCS and group chat support seems to be another sticker, though with a small-form-factor laptop or tablet you should be able to work around that.
The other sticker for me (mentioned in my original post) is voice/SMS/messaging filtering options. The increase in spam / unsolicited contacts across the comms spectrum is immensely frustrating, and few devices / OSs / apps really address the situation adequately and in a privacy-respecting manner. That's still giving me a lot of hesitency on what really ought not to be this complex a decision, though for now I'm thinking it's a good thing to spend the time.
Most of them also have really bad security, for various reasons, including:
- Since virtually no hardware vendor (outside Jolla) supports non-Android phones, they typically use phones that were made by their ODMs as Android phones and rely on kernel/firmware/device trees made available for those Android builds. Sadly, nobody outside Google (PixelOS) and Samsung really cares about giving their kernels and firmware timely updates. So usually the kernel and firmware are full of known holes (Qualcomm and others do monthly bulletins).
- For many reasons, Linux systems have never really focused on proper security isolation and sandboxing. So most of these phones have really poor isolation and you are only one browser/image parsing/... vulnerability away from full phone compromise.
- Unlocked bootloaders or otherwise compromised boot chain. So, it's easy for persistent malware to compromise a phone and there is no way to attest that the system runs unmodified binaries (as you can e.g. can with GrapheneOS' auditor or Android phones with fully verified boot and Strongbox).
Let's say, if I was a bank, I can understand why I would want to block such devices.
So as a bank, you would be forcing your customers into the duopoly of the American megacorps. Thankfully, there are banks that do not do this.
Obviously I want banks to support alternatives, but I can understand if they only want to support secure OSes. Some banks support GrapheneOS remote attestation besides Google Play Integrity at the strong level.