T440 should be great! But its old hardware, so expect things to break after a while...

If you have some RAM and the time to learn then QubesOS could be perfect. Or Virtualbox, with wallets running in a VM that has no network at all.

That is how I keep some of my Bitcoin secure using Electrum cold wallets on this laptop, first I denied it network in Virtualbox itself, then I ripped out all the networking packages inside the VM.

Yeah there might be a keylogger somewhere in theory, but since I am running this using Mullvad on Linux Mint I should be fine. Got most in hardware wallets of course.

Lots of ways to secure things once you are on older hardware and Linux or QubesOS!