Personally I recommend most folks go with a minimum 500 GB hard drive for a Laptop but that's really because I don't want them complaining about it later.
No one ever complains down the road that they have too much space.
However, I've run numerous Laptops on 256 GB drives without issue. In the last few years, as they are so cheap, I uses a couple as test drives during the repair process.
My rule of thumb is you want 1/3 over the total space on the Operating System partition (hard drive) free at all times on a computer. Things will noticeably slow down if you clog up the drive. Win10 (or possibly Win11 in this case) installed only consumes about 20 GB for the 64 Bit version. So what other programs are going to be installed, and how large are they, become a consideration. But it's simple math.
Most of the time, even on brand new Laptops I setup for folks, my habit (it goes back to ages ago to IT at General Electric) is to partition (split) the hard drive in two via software. (Now built in to Windows 10) A "C" drive for the Operating System and Programs - which is typically 100 GB. Sometimes more / sometimes less. The other portion of the drive is "D" for Data. That way if C gets corrupted by a virus, trojan, etc., the Data would still remain readable/recoverable. I've had folks who wanted me to migrated their data, after the computer is 5 years old and beat up; to their shiny new one, and all they have is 20 GB on a 900 GB Drive! So buying a 1TB up front was probably not the most cost effect purchase they ever made.
So the question is 256 GB enough? I know you plan to keep the bulk of your Data (Tunes) on a separate USB Drive (backed up of course), so it may just be. Only you can calculate what Programs and Data you plan to keep on it. Of course in the future you find it too small, all of the major hard drive vendors (Samsung, Western Digital, Seagate, etc.) offer free migration software if you want to go to a larger (1TB? ) drive. Those M.2 drives seem to be still getting cheaper every month, and are simple to swap in.
I hope this is helpful.