Multi-project pipeline + AutoDevOps

I currently have a project that runs two repos - one for its API, and one for the Web app frontend.

Ideally I’d rather keep them as separate projects, as there isn’t a 100% strict one-to-one between the two.

Currently, we use GitLab CI/CD with a standard runner just deploying the code to our servers and call it a day. We have a staging and a production environment, and manage them through branches.

We’re looking to switch to using AutoDevOps with a Kubernetes cluster, to allow for scalability but also review apps.

I know that GitLab has Multi-Project Pipelines and there’s a lot of information under AutoDevOps, but I feel like I can’t quite nail on the head.

Basically, my needs are:

  1. When I deploy one part of my system, the other gets deployed as well (in the future we’re moving towards microservices, so any advice on how to manage things when we get to 3+ projects would be great as well!)
  2. If I somehow get the repo[s] working together, am I able to have a review app created for both my API and Web projects, and then stopped together?
  3. Bonus points: what if I have a feature branch on my Web repo but not my API repo, and I’d just-as-well have my Web repo use a static version of my API? How, reasonably, should I go about adjusting the environment variables accordingly?

Am I crazy? Am I approaching this completely incorrectly?

Thank you in advance for your time, I really appreciate it!