Now, I tried PSFONTS.
To move the folder what I did was, I used the "System Setup-> Fonts" tool to first uninstall all the fonts from PSFONTS. I moved the folder to other location "C:\Resources\Fonts" on my case. And after that I drag and drop them again on "System Setup-> Fonts" to install them again.
It seems to be working. But I'm not sure if that was the right way to do it.
OS/2 (i.e. Presentation Manager) doesn't care in the slightest what directory fonts are installed in, as the complete path to each font file is specificed in the PM_Fonts section of OS2.INI. You can install fonts to anywhere you like, even to multiple directories on multiple drives.
Now, some applications which want to do their own font lookups might default to looking in ?:\PSFONTS - for example I think Ghostscript and/or maybe gsview are by default configured to search for fonts in ?:\PSFONTS and a couple of other well-known paths, and don't use OS2.INI to search for fonts.
Some early and/or app-specific versions of fontconfig also defaulted to looking in ?:\PSFONTS, and I think one or two older versions of Java did as well. Fortunately, current fontconfig/mzfntcfgft versions are smart enough to check the INI file.