Question about Samsung Galaxy A34 5G

Yes, it works fine. The prerequisite is, of course, a corresponding plan.

With a Swiss SIM card, it works without problems in CH, FL, A, D, DK, N, S, F, I. Then everything else will probably work too ;-)

This certainly works everywhere where the technical prerequisites are available.

It supports any network worldwide.

I don't understand the question. Why should it only work in Switzerland? Well, at least it works in Liechtenstein too. ;)
With a Liechtenstein SIM. The product is sold worldwide and I have also seen corresponding test reports on YouTube etc.