I don't know if this counts, but YC funds the Centre for Effective Altruism and 80,000 Hours. CEA, 80k, and OPP are all part of the "effective altruism" ecosystem, and it is not hard to find personal connections between them. (For example, CEA recently launched "EA Funds", which are managed by employees of OPP.)

The connection is not direct. There may be more direct connections between YC and OPP, but I am not aware of any.