You’re aware of low-volume HIIT? Max 15 minutes per day, evidence-based for cardiovascular health same as “normal” exercise. Not for building muscle afaik, and finding your own among the many more-or-less tested ones can be a chore. The popular “Scientific 7-minute workout” and it new versions would probably be a good place to start, and are targeted more for building strength afaik.

pubmed.ncbi.nlm.nih.gov/37939367/ …nytimes.com/…/the-scientific-7-minute-workout/