Upgrading End Devices - What do you think?

Hi all,

I will probably migrate my zigbee sensors to a zigbee2mqtt network to be not vendor locked anymore.
I know the firmware for the coordinator and routers is in active development (appreciate it!) and I can flash those upgrades if I want to.

However - I never read something about upgrading the firmware of end devices. How do you do this? There will be exploitable firmwares out there and as far as I undertsand I have no ability to fix those with zigbee2mqtt, haven’t I?

How to you address that? Do you think my concerns are legit?