Debian minimal netinstall should fit you use case. Long support time, small footprint and should support everything you want to do. Just secure it by having a unprivileged account doing all the stuff you want to do.

With that amount of ram you could make it a hypervisor and host a lot of containers and vms. Maybe proxmox would be a good fit?

Wow thanks. Was missing that for a long time.

Get a used Thinkpad. Shop around eBay for a T480 or T490 which should be at that price range. Solid machines with great Linux compatibility. Anything new will be much worse at that price point. If you desperately searching for something new maybe a HP 255 G9 with a Rzyen 3 would be fitting. Not as good built quality wise and I’m not sure about Linux compatibility but at least it is upgradable. (https://h20195.www2.hp.com/v2/GetDocument.aspx?docname=c08017466)

Thank you for the effort researching all of this!