Ask HN: How do you manage dependencies between multiple repos?

Our company's engineering team is growing and we are also splitting to a few product lines. Currently, each product line has its own Git repo and team.

We manage dependencies by factoring out common code between the repos and put them into a separate repo linked to the product lines' repos with Git submodules.

We also have an infra-as-code repo used by DevOps team for deployment. Keeping track of dependencies between product line repos and this repo has been done manually at this point.

I'm looking for best practices in scaling development to multiple repos and dependencies tracking between them.

Thanks in advance.