Were there any changes in requirements for O visa recently? Did they remove the job offer requirement?

What was quoted below is really just codifying what existed in practice, that is, founders/owners of companies getting sponsored by their own companies. To answer your question, a job offer/employment is still a requirement and I haven't seen any major changes yet in the adjudication of O-1 petitions.

I'm pretty sure the job offer requirement is still in effect, and will remain in effect, since the O is an employment-based visa. What made you think it had changed?