I bought a Dell Latitude E5450 for 350 eur about 2 years back. It was used but looked new. It came with Win 10 Pro, which sits on my NAS as a gzipped bit for bit copy now.
Everything works out of the box on Ubuntu 20.04 and will continue to work until it dies far from now. I can open the thing up and replace everything I would expect I could replace (inc battery). It's all I need speed-wise. If the kids drop it I won't cry. Fun fact: When I play MineCraft with my son (I do it from my work Win 10 computer), he has has booted, started MineCraft and dug a hole to bedrock before I even get to click on the MineCraft icon. The thing is fast and snappy and remains so.
I made accounts for both kids and they can do many things themselves, perhaps because the UI looks more like an iPad than Windows does (i.e., hit the menu and a grid of icons fly in to fill the screen.)
I'm dreading the day they ask for a local install of Office365 though... Or something like Adobe's tools. So far my oldest is 8 and it hasn't happened.