T480 is the standard thinkpad recommendation. It will jump you 5-6 generations of processor forward in time from your x220 and if you avoid the “s” model then both ram slots will be replaceable.

I just looked and the going eBay rate is ~180 for an everything installed/8gb ram example and ~<$100 for no ssd/os. That’s important if you have an ssd in your 220 that’s compatible and can backup and steamroll over it in your new pc. A good set of 2x 16gb 2400 sodimms is about $30.

So you could be up and running on your old ssd with the maximum amount of memory your new system supports for $130 out the door. Pretty cool.

The t480 can also accommodate the google (nee coral) tpu for accelerated onboard machine vision processing and other torch stuff.

Thinkpads after that one generally have one or both ram slots soldered, which isn’t as much of a big deal as people make it out to be.

Other recommendations in the same vein are hp and dell business class laptops, but I don’t know them well enough to point you one direction or another.

Because you’re running Linux already: if you can swing it, consider getting an m1 macbook air. They’re cheap and fast and it’s one more tool in your toolbox.