The current plan is to get a new laptop get everything working there then upgrade old one.
Which windows should I get the new one with? 11 12? whats the freshest and best now?
As said, you can upgrade from Win 8.1 to Win 10.
I'll add that you can easily shrink one partition, install Linux Mint (sorry, purists, but I find it to be the easiest for Windows users) and put an Electrum there (copy the appimage and allow its execution).
I'll also add that you can write Tails OS onto an USB stick and boot from it.
...Maybe that Win 8.1 just no longer worth the hassle, you know...
PS. Latest is Win 11, if you really want to go on that path.