Answer by taking a quote from the following article:

Rundgren was born in Philadelphia, Pennsylvania, the son of Ruth (nee Fleck; April 29, 1922 - April 6, 2016) and Harry W. Rundgren (1917-1996). He grew up in Upper Darby. His father was of half Swedish and half Austrian descent, and his mother was mostly of German descent. Todd was a 1966 graduate of Upper Darby High School.

Rundgren's unhappiness with the production on the Nazz recordings prompted him to educate himself in audio engineering and production, and after leaving the Nazz in 1969, he relocated to New York, signed with Albert Grossman and began working as a producer for other groups, as well as recording his own material, which was initially released through the Ampex Records label (a short-lived joint venture between Grossman and the Ampex company). He also apparently considered working as a computer programmer. Subsequently, he became one of the first artists signed to Grossman's Bearsville Records label (distributed through Warner Bros. Records). After signing with Bearsville, Rundgren worked almost constantly on production projects through the early 1970s. His first project for Bearsville was a Philadelphia band called The American Dream, followed by a trip to Nashville to produce Ian and Sylvia Tyson's group Great Speckled Bird, with a backing band featuring guitarist Amos Garrett, pedal steel player Buddy Cage, pianist David Briggs and bassist Norbert Putnam and drummer N. D. Smart, with whom Rundgren worked on several later projects. During this period, Rundgren also made an abortive attempt to record with Janis Joplin and her band for Joplin's next studio album, but the sessions came to nothing and the project was eventually taken over by Paul A. Rothchild; the result was Joplin's final LP Pearl, which Rothchild pieced together from the incomplete session tapes, following the singer's death from a heroin overdose. Grossman recommended Rundgren to Robbie Robertson of The Band as the engineer for an album Robertson was producing, by singer-songwriter Jesse Winchester, who was at the time living in exile in Canada to avoid the draft. This was followed by a live album for the Paul Butterfield Blues Band. Having impressed Robertson with his work on the Winchester LP, Rundgren was then asked to engineer The Band's third album, Stage Fright, which was recorded in a series of sessions at the Woodstock Playhouse. One of these was attended by New York writer Patti Smith, and their chance meeting led to an enduring friendship. Smith wrote several strongly positive reviews of Rundgren's early solo work in the rock press, and in 1979 Rundgren produced the final Patti Smith Group album Wave. His work for The Band was followed by a second album for Winchester (which was then shelved for two years) and the album Taking Care of Business by the James Cotton Blues Band. This project resulted in Rundgren meeting Cotton's keyboard player Mark "Moogy" Klingman, who in turn introduced Rundgren to keyboard player Ralph Schuckett, both of whom worked extensively with Rundgren over the next few years. CANNOTANSWER

Did he produce outside of Bearsville?

Rundgren also made an abortive attempt to record with Janis Joplin