B2B vs B2C(mobile apps)

It's difficult because not much is open source. Most b2b applications are proprietary. Maybe you can try asking specific questions in developer communities without revealing sensitive information.

What kind of b2b are you working on exactly?

For B2B few practices have been
To get early adopters.
Hire people from the industry/ or someone with relevant experience exp..not prevalent now as product managers can do it all 😀
Hire /Consult with experts in the area
Just get direct feedback from customer - one to one , forums , etc
Ask the customer success / support teams

For your specific instance on Dashboard - try using goal metric framework

I'm working in b2b SaaS had same issue it's hard to get any deisgna in open source

Speaking from personal experience, you can search on YouTube for videos/walkthroughs of SaaS dashboards that are too complex to use.

If not, my approach is to take it module by module instead of creating the full app at once. I'd design a module, test it out with a small group of users, take feedback, implement and test again.