Pilot reported severe weather and hail during cruise flight leading to temporary loss of control.

Narrative

During cruise flight en-route to destination ZZZ1 at 11;000 MSL and in the vicinity of Location A; scattered convective activity persisted along our cleared route of flight. In an effort to deviate away from a visually acquired build up ahead; I requested a radar vector away from ground radar returns. ZZZ Center issued a heading of 075 to avoid weather which was consistent with the visual picture we had while in VMC. Within a few minutes on the vector; the aircraft re-entered IMC and with in approximately 1-2 minutes experienced a strong updraft followed by heavy rain and then hail which lasted for 30-60 seconds. Severe turbulence made altitude control not possible and I obtained clearance from ZZZ [Center] for any altitude. Upon exiting the hail encounter; I requested the field conditions at the nearest airports and ZZZ2 was suggested. Due to local knowledge and lack of emergency services however; a diversion to the nearest suitable field with an ILS and CFR resulted in selection and uneventful approach and landing to ZZZ3.This aircraft was not equipped with airborne weather radar. This could have been a primary tool that might have depicted the threat of hail or heavy precipitation on the vectored heading and in IMC.