No idea where truck is going, it'll take me quite some time to tinker with CAD I think, it left me quite a bitter taste...
Fornjot seems to be doing good, I'm donating to them and I get regular updates (you should too!). Still, there's a long, long road ahead
If I were to do this all over again I'd either go the OCCT route (like chili3d or zoo) or solvespace. they're both "lacking" kernels if you compare them to the commercial ones, but I think there's enough "market gap" for makers that would prefer a sustainable CAD format instead of perfect fillets (and IMO freecad is not the solution).
Keep in mind though that my efforts where laser focused on non-math stuff. From what I gathered from my time in cadmium, b-rep kernels are hard in an unsustainable level. Browser level unsustainable. I just hope that out of seer necessity we'll find another way to solve the CAD problem, instead of a b-rep kernel
can you tell us more about the use cases that you have in mind? I saw that you're able to run 1-4B models (which is impressive!)