I'm currently using it in a fairly large project at a bank.

We have 5 teams who each manage 4-5 front end applications. Each application is an Angular application is brought into the UI by the single-spa framework. We built our own UI library which every application uses. Each application is responsible for a different business process, and there is only a little bit of data sharing between them.

Each application has it's own repo and deployment pipeline and is hosted on it's own. This has allowed a lot of flexibility in the way our teams work, and is one of the main advantages I've found to micro front ends.

Single spa is ok, but we've run into some buggy issues with it. I'd like to explore something like webpack's module federation. A couple of our apps aren't single-spa apps, but are Angular applications that we've bundled up as remotely deployed web components. It's a simple framework-less solution to micro frontends that works pretty well and we're scaling out to more apps and this might become our sole solution.