The problem with the intrapreneurship idea is that it's really hard to beat desperation as a motivator. I have seen people behave very differently in the context of a startup vs a corporate research lab thanks to this dynamic. Some people thrive in the corporate R&D environment, but the innovator's dilemma eventually gets to their managers.
Cisco has done a great job balancing this, actually - they keep contact with engineers who leave to do startups, and then acquire their companies if they become successful enough to prove the product.
After a bunch of ex-Cisco people ate Cisco’s core router lunch at Juniper, Cisco vowed it would never happen again. Until a bunch of ex-Cisco people ate WebEx’s lunch at Zoom.
Getting a big seed round once makes you want that next round to keep going (and take even more money off the table).
Getting a X-million-per-year budget from a parent company gives you a very different sort of situation. IME this results in less urge to get something out the door and more urge to get "the best thing" built. Shipping early risks your budget in a way that "look at all this cool theoretical progress" doesn't, because the public and press can critique you more directly.
Lack of major owner equity basically means few intrapreneur efforts will succeed unless the 'founder' really couldn't succeed without the daddy company
Cisco has done a great job balancing this, actually - they keep contact with engineers who leave to do startups, and then acquire their companies if they become successful enough to prove the product.