On ubuntu 24.04, installing the package fonts-urw-base35 doesn't put anything in /usr/share/fonts/type1/gsfonts. So, even with that installed, any call to gm convert -draw 'text' omitting a font or specifying a font name results in gm convert: Unable to read font (/usr/share/fonts/type1/gsfonts/n019003l.pfb). Explicitly setting the path to a font file does work.