Local print shop that deals with large/poster prints. They'll usually be happy with a high enough resolution PNG, and can advise you on what's the best way to print in the physical size you want - what material to print onto, what printing approach to use, what finish to do, how to frame it, etc.

That is kind of the thing.

Getting the image is trivial. The real effort is getting it printed and getting a frame for it. And the cost of that tends to be pretty close to just buying a pre-print. And stuff like this tends to be sold in museums or other local/government buildings and genuinely goes towards some great community programs.

That said, there are some great sites for this. There are cheaper websites, but Stackhouse is generally a great choice for printing. Especially if ou want a canvas print. Frames you are almost always best off going to a pawn shop or local art supply store, but even amazon is not a bad choice for that.

Combine that with realizing just how many museums upload high quality scans of genuine works of art and...