Yes, you’re correct they are both cooperative type of organization. They are also integral part of the Swiss culture and identity, and are present all over the country, it’s not uncommon to find a Migros in a small village where you wouldn’t expect one.

Note that Switzerland is really a weird country, it’s difficult to compare it with other places.

Looking at Finnish https://en.wikipedia.org/wiki/S_Group which is cooperative of cooperative. The prices aren't that much better than the competing group of privately owned shops.

And I always wondered if the goal is to provide service to customers/"owners" why are they expanding outside their geographical areas like to other countries.

Tacit collusion is what duopolies are all about.

Same family, but post-dispute. IIRC.