What are the chances of getting sti/monkeypox following 2 x kiss and anal/penis (non penetrative) masturbation with 2 men?

No way to know without more information. What is the setting and nature of partnerships (friends, bar pick-ups, sex venue like a bath house)? Frequency of MPX so far in the city or town where you are located? Have you been vaccinated? Most STIs are rare without penetration, but not MPX: transmission only requires genital, anal, or oral contact. You might check with your local GUM clinic.