You recently got promoted so your manager likes you and you are in a good spot on your team. So I wouldn't change teams. I wouldn't talk to your manager about

You recently got promoted so your manager likes you and you are in a good spot on your team. So I wouldn't change teams. I wouldn't talk to your manager about working on stuff you want or mention leaving to work on side projects. Focus on your job for now, save even more and test out doing side projects on your own. Check what documents you have regarding IP for things you work on outside of work on your own hardware. I wouldn't raise a red flag by asking this question through HR. You might like this podcast StartUpsForTheRestOfUs.com listen to the archive. I would start building some simple side projects that can earn some money and build up your skills and experience in that area following a stair step approach. Rob outlines it on StartUpsForTheRestOfUs.com. Once you have a few wins under your belt you can think about leaving your FAANG job in the future to start a SaaS or other project that you feel has a high probability of success and generating quit your job money. Good luck with your transition.