How big a print can I make of a digital drawing?

I've used Procreate to make a number of drawings on my first-gen iPad Pro (using the "screen size" setting of 2,038 x 2,732), and I'd like to print tests of several of them in a large format (local commercial print shop offers 4' x 3'). According to an earlier Ask question re: large-format prints of photos, I found the formula of dividing the pixel size by 300 to get the largest good-looking size for a print.

This would seem to nix my planned print size, but does the same formula apply to non-photo graphics?

Thanks in advance.