While a lot of the analysis is done here using python scripts, fast backends are best done at the C or fortran level. I’m not quite sure which category this should go into, but Gnuastro-0.22 has just been released a few days ago:
This would make most sense for LSST/Rubin data on the photometry images, since there are many photometry tools usable from the command line. Gnuastro is FOSS, so redistributable in modified form like any FOSS.
I’ve only done a few fixes on the FLRW part, not the main components which are for photometry.
quick start: Quick start (GNU Astronomy Utilities)
install in Debian or a typical Debian derivative: apt install gnuastro