Next year Windows 10 goes End of Life. Microsoft will undoubtedly push windows 11 hard, but a lot of machines won’t support it leading to a few economic points of interest:
The demand for new machines will be high, driving up cost.
The supply of unsupported machines will be high, driving down the used market.
Are you all ready?
Proton is really a WINE fork intended specifically for Steam games. Most of the changes in it target games. You may hear a lot about Proton having good compatibility because, historically, games were where WINE tended to have compatibility issues, and Valve put a lot of work into fixing that, so it’s more that Proton just improved the situation specifically for games a lot recently.
WINE might be able to run the program, would be what I’d try rather than Proton. You can technically run Proton without Steam, but it’s not really designed for that.
Or you might be able to run a Windows VM on newer hardware and run it on that, would be my fallback attempt. Less seamless than just having a Windows program open a window alongside Linux ones, but sometimes that can work if WINE can’t do it.
I’d see if Linux can recognize the label printer, if this is a really ancient printer. That’d be my first step. Then look into having Windows apps print to said printer.