Outbound trip from Germany

Yes, you can take whatever route you want, there is no rule that says you can’t make some stops as you go, as long as the pass is valid on the trains you use.

There is a kind of more or less also enforced rule that one should use the direct route from start till border/airport/seaport without long detours. But with the new mobile passes this is much harder to check and in the past there were only some very isolated reports that only large+expensive countries (mostly UK, also DE) were really enforcing this. So start from B/suburban you should not go via M or F to NL. Criss-crossing in B on the S-bahn before setting off is strictly speaking not allowed.

When using the mobile pass you simply have 2 travel days where you can use the pass in an unlimited way in your own country as well as the remaining countries.

Whilst the principle is that you use it to assist your Interrail journeys it is entirely up to you how you interpret this and border crossing is not monitored in any way - with a mobile pass that is. I used mine for 2 returns to the UK, after flying out, with no problem.

I