Turris Omnia, convert to dual firmware layout

I upgraded from Linksys WRT-1900ACv1 to Turris Omnia. There is only one thing I don't like: partition layout. I really really linked the Linksys dual firmware / dual boot layout. I do a lot of playing around with OpenWrt and, at the end of the day, it is very nice to have a known stable firmware to return to.

Is it possible to convert Turris Omnia (or any other mmc-based router) to dual firmware? I can modify uboot scripts myself, but I don't know where to look in OpenWrt sources to make it generate dual-firmware sysupgrade images, or how sysupgrade determines where to write those images.

As an alternative, is it possible to make OpenWrt generate squashfs files that contain just the root filesystem? I would enlarge mmcblk0p1, put both kernels and both rootfs/squashfs images there, and update them manually. Booting would be done from uboot the same way LibreELEC does.

Thanks.

I dislike the feature request and vote against spending developer hours into some dual firmware layout.

Thats what in OpenWrt backups and failsafe boot mode is for. https://openwrt.org/docs/guide-user/troubleshooting/failsafe_and_factory_reset
If you break something, then boot into failsafe mode and revert to your known stable state you made a backup from.

Booting into the failsafe requires for me to get up from my couch, bring a ladder from the garage, climb the ladder to get to the router and hold the button, climb down, go back to the couch, ssh and fix the router, go back up and press reset again (because failsafe doesn't support reboot), and then take the ladder back to the garage.
But I'm a couch potato. :sweat_smile: I don't want to get off my couch. I want to wait until the watchdog resets three times and it auto-boots the backup kernel and partition.

There is no need to spend developer hours. This is not a feature request, as I am not interested in changing any other router than mine. It only takes a few minutes to tell me where to look.

EDIT:
Ah, sorry, I was thinking about Omnia's failsafe partition, not OpenWrt failsafe mode.
OpenWrt failsafe would be a no-go from the start, as I usually break the kernel or sometimes the very early init, not the configuration.