Ouch. I also live in a city where bike thefts are … fuck, just part of life. Which is a horrible norm to have to accept.
You’re right that a grinder-proof lock does not exist. Having read reviews and listening to bike shop owner experiences (they hear everything) … I have Kryptonites, motorcycle chains, Abus folding locks, but my personal favourite that I’m “trusting” (ha, delusions) is the Hiplok DX1000. Check it out. As good or better grinder results than nearly all others, it seems. But nothing is grind/pry/jack-proof.