SPAC seems preferable for companies with an inexperienced board or who are trying to hide something from the public before listing their stock.

I imagine SpaceX will eventually go public via more traditional means and there's a good chance it's the first trillion dollar IPO IMHO.

None of those space companies are doing anything like SpaceX. You might as well just buy $GOOGL which had a 5-10% stake (probably some dilution now) in SpaceX. Although that value is probably only 1% of $GOOGL so you better hope SpaceX 100x’s for a 2x $GOOGL gain.

a few are being used currently by spaceX for last mile delivery.

Space industry will a money black hole for a while longer IMO. I suppose it didn't really matter to every other disruptive startup so maybe stocks only go up /s

If you want to invest in SpaceX, Fidelity has some funds that are basically S&P500+SpaceX. SpaceX is a small percent of the funds (like 0.5%), but if you were gonna invest in Apple/Facebook/Amazon/Visa anyways that's not the end of the world