Marketplace on Symfony - what to take as a basis?

Question

symfony

It is necessary to develop a rather specific marketplace. You don't want to start from scratch. It’s also dumb to take hardened dinosaurs like OpenCart as a basis in the days of php 7.3 and new cool frameworks.
I know that under Symfony there are at least 3 online stores that are more constructors than ready-made solutions. But they have a lot of downsides.
Question to the community - where would you start in this case?
ps Yes, I know this is not the first question. And not even the tenth. But, unfortunately, I can imagine the complexity of such a project, so it’s better to overdo it than to make the wrong choice simply because some solution is not popular enough and was not found at the design stage.