I fully understand. In fact, a few months back that is exactly where I landed as well (Legal advice: avoiding the Google EULA?). I didn’t have the legal base to know what the EULA would affect. And I got (almost) no feedback. At least nothing to help clear up the situation.
If it is any motivation: I can assure you that if these rebuilds succeed (including from a legal perspective) then there will be many people interested in this. It would not surprise me if F-Droid would start using them or at least offer it as an option for building submitted apps. Personally, I have been slowly porting a pretty large project of mine to android, with the intent on eventually releasing it on F-Droid. But I will only do so officially when we have an open SDK+NDK. If we fail, I will probably put this porting effort back in hibernation.
I guess we have to start seeking legal feedback on this. Given how important an open SDK+NDK would be for F-Droid, perhaps they can provide some insight? I am surprised they have not responded to this, but it’s a tricky subject. We also could reach out to FSFE since they can help with legal support. There’s the Software Freedom Conservacy. And I think FSF itself might be able to give some feedback.
I still feel somewhat hopeful about this. Given the size and legal department of google, I would imagine they would not overlook the way the build system copied the licenses to NOTICE files and make sure it includes everything relevant. The fact that so many of the packages then don’t have an EULA seems to indicate they know it doesn’t apply.
If this is true, which we would need reliable feedback on, then the remaining build-tools that does contain an EULA could be worked around if it is affected by the EULA. At least the programs in it (and their sources are not under any EULA from what I’ve seen) and can be built independently of the SDK (in fact, google offer separate git repos with prebuilt binaries of these for CI pipelines).
However, build-tools does seem to contain one further part that is not one of the programs. It’s called “renderscript” and appears to be a deprecated thing. But this might actually be why the EULA exists in this specific zip?
What can I say? Sounds like you got an awesome brother. Anyway, the obvious challenges with building everything from source all the way down is a big and interesting topic. It’s often called “bootstrapping”. And if you want a break and read something completely different and impressive, I highly recommend looking at this, it’s quite a wild ride: