Xdvipdfmx doesn't find .pro files

I’m trying to get tectonic to compile a complex document that uses a lot of diagrams generated with pstricks. I’ve been adding .sty and .tex files from the pstricks package next to my main document incrementally, as tectonic complains that it doesn’t have them. It’s now to the point where it has completed running through the document with the tex compiler, and is running xdvipdfmx, which complains that it can’t find, e.g. pstricks.pro (among others), even though I have also placed these .pro files in the same directory. Also, I have texlive installed, and kpsewhich finds these files in, e.g. /usr/share/texmf-dist/dvips/pstricks/pstricks.pro . I suppose that tectonic has its own custom version of xdvipdfmx which doesn’t use kpsewhich. Can anyone advise how to make tectonic aware of these files?

Edit: I should mention that this document compiles successfully with standard XeTeX. Also, I did a little research, and it looks like tectonic uses the stock xdvipdfmx from XeTeX, so it should in principle be able to handle the same document. I just need to learn how to make the .pro files available to it.

Edit 2: I duplicated this post in the Github discussions for tectonic, since I learned that this site is being de-emphasized in favor of the former.