Have a lot of engineer & founder friends I talk to regularly. I think overall goal would be to go one step up from connecting and actually be a peer in some respects.
Build up skillset to be a founder-operator in the future. Along the way, I'm sure it's helpful to the day job in investing.
Re: 1. Definitely not this. I've realized my skillset / interests don't coincide with writing code at Big_Tech for a living.
RE 4. Have tried a lot of those programs. They don't click after the beginning stages, and don't do a good job graduating you or tracking you. Also intrinsic motivation is a problem -- i'd like to take a half year off to just do that.
RE 2 and 3: These are good ideas. Have been doing them to some extent. But taking next step of being in community -> contributing to it.