We used to have to draw sprites for custom fonts, using special code to convert text to sprites, now it’s all handled for us! (but you have to draw glyphs as binary numbers, like 0b01110 for the first row of A, or use a cart tool to generate code from sprites — a few of us are making such tools).
I will send you a text file and a PICO-8 cart with the commands to define the font in PICO-8 and the link to the BBS thread when I complete my tool. Thanks for the permission!