The US has lived under that very scenario for over 50 years with Cuba. In return for the Soviets removing the warheads (that we could monitor), the US was -- and remains to this day -- forbidden from any military intervention against the Communist government, whether through direct invasion or by US-backed insurgency.
Would Russia under Putin agree to such terms for Ukraine? More importantly, would TNF agree to such terms for Russia for Ukraine?
To be fair, the Soviets were willing to live with hostile neighboring states such as Turkey. While Putin his his Soviet predecessors were aggressive with weaker countries, they tended to be able to reason.