Due to historical context implementation of static front pages in WordPress is, simply put, a horror. This is not something it was meant to do originally and the way it was bolted on at a certain point is opposite of smooth.
Under these constraints it would be hard to impossible to say what would be the “perfect” approach. You are dealing with very imperfect situation already and core is not opinionated about implementation details, so there is little guidance.
I would say your approach should not be technically driven, it should be designed first. One niche’s idea of modular front page could be quite different from other’s.
- Start with a design (by which I mean design, not just a pretty look).
- Clarify as much as possible desired functionality of the blocks.
- Evaluate possible technical implementation based on those needs.