Do you have remote hands that can install a micro SD reader and SD card? One of the users here mentioned using rpi-clone (https://github.com/billw2/rpi-clone) and running a nightly clone. If the primary card fails, simply power off, switch cards & reboot - then re-image the wonky card or replace it with the new running system. So far this has worked out pretty well for me since I started using it.
I have a number of remote stations and I’m always worried about them dying - but outside of tools that I add after the install I try to treat the pi as ephemeral data - since all you really need to restore is the FA ID key to get it back in the game. I run a few nightly crons that reach out to the remote nodes, make simple copies of configs to a central local pi and keep my fingers crossed
On really remote stations I’ve also installed VNC + Paid for a 10 seat VNC license (~50.00 US/year) – so if my openvpn setup fails for some reason & the pi remains on the network I can almost always still use the VNC cloud connect to get to the host to help it.