What does being a Bihari mean to you because it's not a primordial identity that has always existed. The land of what is now Bihar was once the power centre of South Asia with powerful kingdom of Magadha. Some of the greatest dynasties that have ruled over India like Guptas and the Mauryas come from Bihar. Nalanda was one of the great learning centres. We know the importance of Bihar in the development of Buddhism and Jainism. Not everyone who calls himself a Bihari today is a descendant of these rulers and figures, but if you treasure association with the place then surely there is much to be proud of in a good way about the region of Bihar.
Sher Shah Suri, though an Afghan, was born in Sasaram and that's where his tomb is as well. Unlike Mughals, who receive a lot of hate, Sher Shah is comparatively more liked. Bihar is also the land of prominent Sufis who played an important role in propagation of Islam like Makhdoom Sharfuddin Shaikh. In the modern period, when Bihari regional identity began to emerge and crystallise, there were many prominent muslim figures that emerged from Bihar. Read through Mohammad Sajjad's book on Muslim politics of Bihar. Muslims of Bihar have also contributed in literature and culture of vernacular languages as well as Urdu. Biharis are known for their work ethic.
I guess it all depends on what do you want to be proud of. If you are trying to find if you were a descendant of some ruler or high literary or religious figure then for 99.99% of the people that's never going to be the case.
Though I noticed you did end up joining - welcome! There was a bit of a problem with the new member greeting system so it must've looked like a blank page - sorry about that we fixed it and it should be running fine now if you check back.
Another app
This one
It gives accurate details of each and every vehicle's owner.
Even Truecaller is misused
Even if you don't download Truecaller, still Truecaller has your information.
For example: Your Freind has Truecaller installed in his mobile, he also has your number saved. Truecaller can access his Contacts so automatically your number will be added to Truecaller even if you don't want to.