"John Fullsauce" is the name given to an individual who goes by JohnnyMonke(confirmed in geoguessr #2) who has been managing The Full Sauce and The Extra Sauce channels since Vappy's departure.
John revealed his voice in a video about the Full Sauce channel's community guideline strikes on June 20, 2020. It is best described as "vaguely European".
Videos
External links
John Fullsauce on the Vinebooru