Android is getting a lot of bad press just now regarding older versions of the software and the fact that there is so many older phones in circulation. The warning is that your phone could be more susceptible to hacking if your Android OS is older than version 7.
A Linux phone may be a better alternative one day, but I believe that the updating of the software should follow the same system as Apple - launching new versions of the operating system to one brand of Linux phone by year and advising consumers which older models would not be updated. As Apple, the manufacturer would know exactly what hardware your Linux 1, 2, or 3 phone (as an example) would have and the operating system would work as it should.
Perhaps if there was a unique operating system for Linux phones, it could also be incorporated in a fully fledged desktop distro too. The main drawback to an early adoption of the Linux phone is the lack of apps similar to those of the Google store, unless these apps can also be run in the Linux environment?
It's a case of 'watch this space', I'd certainly be interested in a Linux phone once it has been fully launched.