If the level of detail in printed topo maps satisfies you, then Outdooractive Pro seems to cover that, at least for some countries. It claims to have Swisstopo, Kompass, DAV/ÖAV, as well as a range of "digitalized official topo maps" which include DTK, ÖK, IGN, OS, Harvey, and some for Slovenia and Italy which I cannot really judge.
I haven't tried it myself, but you can set up a free trial account. (I'm not affiliated in any way with them.)