With your 20 years experience if you really want 2.9.5 on arm you can always build it yourself.

As for the version differences that will depend on the system the packages were built on.
Was there any reason, apart from the official arm image being based on Bookworm, that you went with Raspberry Pi OS Lite ?
Does that give you the choice of Wayland or X11.
Look we get a lot of users with varying degrees of Linux Experience, as we can't tell your experience usually we start advice with the basics. So no it's not a waste of time starting with said basics.
From memory when I attempted to build an RPi image based on Devuan, based on Trixie or maybe unstable, there was an issue with the libgpiod library. At the time the libgpiod driver would not compile against version 2.0 so I abandoned that idea due to that. As far as I know I'm unaware of that situation has changed. Bear in mind that there are some issues that affect Axis in 2.9.5 and 2.9.6 that have been well reported on the forum. It would appear they have been resolved but looks like we need to wait for a 2.9.7 version.