Sorry to burst your bubble, but I'm pretty sure the BB-8 you see on film is mostly CGI. A working BB-8 prop does exist but it's more of a reference that gets covered in CGI. It's a common film technique that gets used these days and often those articles praising "no CGI" are often PR bullshit that stretches the truth because "practical effects" has become a buzzword.

I can prove a few shots of BB8 are CGI.

Shot1

Shot2

Shot3 - CGI + possible practical (the lighting on the body of BB8 changes in CGI pass but idk if that confirms they CGIed the body too)

Shot4 - Notes in bottom left confirm

I obviously can't prove it but I would assume every BB8 shot is either entirely CGI or uses the practical robot as a reference pass. Relying on a practical robot would introduce a point of failure that could delay shots and force more takes, adding cost and time to the production. The only reason the filmmakers have to use a practical effect is to give the actors a reference, all other shots it's faster and cheaper to use CGI.

TL;DR: BB8 is mostly if not entirely CG and film companies are almost always lying when emphasizing the practical effects used in their film.