Hi Sabastian,

Sounds like a great trip and the weather is looking good from around Wednesday onwards.
Here is a good route that takes you all the way around the fjord from Bergen:

https://ridewithgps.com/routes/42464973?privacy_code=vOhmcNV1Hc2SlVJX

Trolltunga is the most famous route in the area. The season usually starts on 1 June (Although expect snow on the tracks). You can cycle part of it. It is an all-day hike (8-9 hours return trip)

The other famous hike is called HM Queen Sonja’s panoramic hiking trail.

You can find info about them and others here: https://hardangerfjord.com/en/articles/reisetips/5-handplukka-turar-i-hardanger-2

When it comes to wild camping Hardanger is not the ideal fjord. It has a lot of farms around it and many areas just aren’t accessible for camping. I usually use campsites but you can find wild camping spots if you search well. There are some tunnels that have small roads around them – I know some people camp there (no one uses them).

You can also search on this site for some free camping places.
https://www.ioverlander.com

Lastly, Norcamp app is the best for info on all campsites in Norway.
https://play.google.com/store/apps/details?id=de.schwarzstoff.norcamps&hl=en&pli=1