Can I give a shameless plug to my new favourite tool
https://amzn.eu/d/hopQWZOWifey bought me one of these a couple of months ago, initially unimpressed as it feels a bit cheap and toylike. My does it do a good job, must have used it 10 or 12 times on the same charge and the first disc. It’s cut bolts, stainless sheet, mild steel sheet, piano wire and most recently I managed to get it into and really tight spot to grind off a seized and rounded nut on the drip link of our golf.
Cracking little thing, highly recommended (hope the link works)