It's super common with non-profits. Obviously they would prefer no strings attached but some light strings are usually not a problem for most non-profits.
That would have been hard since both of those projects came out after Django, but just an FYI Jinja2 templates are supported and nothing stops you from using SQLAlchemy. Granted you lose a lot of the tight intergration that makes Django great to use.
It takes 5 minutes to switch most projects. And less to go back to pip. Seems silly to waste a bunch of wall time when using pip when there is a super easy alternative that doesn't have high switching costs.