Maybe this is a hot take. However, a lot of the Chromebooks that were deployed by schools during covid are build like tanks while being super lightweight and having great battery life. Meanwhile the old thinkpads are 10 years old and are probably starting to wear down. Many Chromebooks support coreboot these days so theoretically they have the potential to be more private and secure. Some of them are also arm which means that they are more efficient from an architecture perspective.
Edit:
I like how incredibly controversial this is. I have successfully split the votes
https://docs.mrchromebox.tech/
A lot of Chromebooks can have Linux natively put on them.
I see a lot of pooh-poohing of the idea in this thread, but I think there’s people who are willing to do so.
I just took an old Lenovo ThinkCentre Chromebox 10H5 and modified the UEFI firmware with the walkthru from MrChromebox to put Xubuntu on it. It’s actually pretty snappy despite its limited hardware.
Also, I upgraded the 16gb M.2 SSD into a far more sufficient 256gb size.
The shortage of RAM is rough, but it can still be a workhorse in a lot of ways. I plan on replacing Xubuntu with a server version to get a little boost out of running it headless to drop the RAM going to rendering a GUI.
I would with Debian plus minimal gnome (install just the gnome base package without recommends)
Another idea is to connect it to a much faster device over RDP or moonlight