Everyone thinks because they can create "small reusable slices" of full frontend code that this comes for free without a load of problems that get in the way of the mythical land. The only issue is everyone who has tried microfrontends is universally full of regret.
Other attempts at this are:
1) having an enforced centralised library of components (this just about works) - how this is managed and the engagement with other teams is critical.
2) turn everything into an npm package and create version hell at the end of a sprint as hundreds of devs try to version bump everything and the main package.json all at the same time.
3) free for all with moving people regularly between teams. This is the best solution because best practices automatically filter their way through each team through the people and everyone learns and gets on with each other in a human way that allows real collaboration.
4) splitting vertically rather than by components so one team does the search UI another does the homepage another does the product detail etc. but hopefully in the same technology!
Or you could probably just reduce the number of people adding pointless features to your ecommerce site... Ah there is five of you and you did microfrontends didn't you, I can't and won't help you then :-/