Removing old 531 frame bottom bracket. Where to source a pin spanner etc
Non-cycling-specific pin spanners do indeed tend to have fatter pins, but in the cycling section you should find something.
Park Tools SPA-2, for example, has pins just over 2mm diameter (so you should check), and the spacing is adjustable over a small range about what you need because its a little springy. I bought mine for working on a 90s Raleigh; they're not needed so often on modern bikes.
Hopefully you'll need less force than to remove the lock ring, as it's not a massive tool.
Alternatively it's possible to measure the spacing of an opposite pair of pin holes and make something from scrap metal using M2 screws as pins. That's only worth it if you've got all the tools and materials to hand