You might want LTS and upgrade some packages when needed/forced and not play the "update" lottery. New updates not only bring you cool new feature and fixes , they bring new bugs and sometimes features are removed or GUIs are moved around. At least with my LTS I worked around for existing bugs , upgraded from PPA the things I needed to, browsers are latest versions and my IDE is auto-updating too.

Stable base. I'm pretty fond of Ubuntu LTS as the OS running the bare metal, then [docker] containers on top of that to run applications, which means I can have as new of apps as I want while keeping a nice boring stable kernel/bootloader/sshd/whatever.

I'm not sure I understand. You want a stable host system without the need for forced, sometimes breaking, upgrades - so an lts release "on the outside".

You want to develop with new tooling, so a newer release under lxd/lxc. But you probably want to deploy on an lts release - maybe the one comming in a year?

You could of course develop under arch in lxd/lxc - then validate for an lts release once your code is "done".

But I don't think you'd generally would want to deploy to arch - as you'd have to play catch-up in order to keep up with security patches (or backport yourself)?