Can you leave a zimmun (10 or 3) to daven with a minyan (no minyan later and there will be zimmun and minyan without you)?
No, it is not permitted to leave a zimmun for this purpose.
Davening with a minyan is a virtue but not a full obligation (though see Iggros Moshe Vol. 3, no. 7), whereas a zimmus is actually an obligation.
Therefore, one cannot leave a zimmun for purposes of joining a minyan (even if we see davening with a minyan as an obligation, it won’t trump the present obligation of zimmun). Please see our articles on Zimmun for more information about the obligation.