I think NLNet is pretty good (I helped on https://nlnet.nl/project/xrsh/ and now working on my own https://nlnet.nl/project/ImmersiveXP/ ) but otherwise I only know at the local level, e.g. subsidies in Brussels e.g. https://www.innoviris.brussels (I'm in touch with but didn't formally apply yet).

You might also want to try https://www.sovereign.tech/programs/fund which isn't limited to Germany AFAICT but does focus on infrastructure.