Basically years ago FOSS made things simpler because it gave you back control.
Now maybe I am just out of the loop, but I am not feeling the control in the everyday.
I've been using OpenWRT (previously DD-WRT) on my routers for years now. Mostly I just enjoy not having nonsense on my router!
I think how I got started with it was by finding my device in their devices table and reading the page specifically for it. https://openwrt.org/toh/start
The biggest caveats would be: I've never had any issues personally, but be aware of the risks; avoid bricking your router, and be prepared to recover it in case the worst happens (make sure you back up the firmware before flashing it.)
And once you're installed.... `opkg upgrade` is much riskier than `dnf upgrade`. There's usually no script doing necessary modifications for you. Use with care.
I dug out an old router in the garage and might play over the weekend