They are quite robust and long-lived. You can get 10 years out of a PC and 5 years out of a (decent quality) phone.
The PC I'm in the process of replacing[1] is ~10 years old.
I do have a cellphone (rather than a computer with audio); I dropped the last one off my roof onto concrete, and it survived.
But I wasn't really thinking of "robust" in mechanical terms. More like
https://www.bbc.co.uk/news/technology-50747526 "BBC iPlayer stops working on some Samsung TVs Samsung said the problem had been caused by "security certificates" expiring on Sunday". Or Microsoft's "PlaysForSure (TM)" music [sic].
[1] the new incarnation (Ryzen 3700x, x570) is functional but awating final choice of operating system. I've tried centos and found it to be a bit of a pain. I've tried ubuntu 20.04, but dislike the snaps concept. OpenSUSE seems quite reasonable, particularly YAST, and I used it before I switched to Ubuntu. Linux Mint with xfce also seems good, but I'll wait for the new LTS variant to be issued "in June". If Win10 doesn't get uppity with me, I'll keep that around too.
There's only been one disappointment. I decided to play around with Joanna Rutkowska's Qubes, simply because it is so different and pushes one concept to the limit. Unfortunately it only likes inbuilt graphics and some Radeon cards, and I have an Nvidia. The core is that it Qubes, very reasonably, doesn't trust binary blobs.