yep stop thinking in large, illogical measuring system and start using millimetres. Slicers can convert inches to mm - but most automatially assume you're being sensible and using mm to start with.

In answer to how small you can go - there was a normal sized wristwatch (ie: NOT smart watch size) printed in fdm at tct last year. Admittedly they did go down to 0.1mm nozzles. But all the teeny tiny parts were printed in plastic. amazing thing.
Was demonstrating some enclosed delta machines.

I've personally printed 8 toothed gears 5 mm across with 1mm central hole, rubber tyres 3mm across with 1mm axle hole and 1mm thick.
For that project i ended up with 5 individual parts which could all comfortably fit on a dime - printed around 100 of each, so it's repeatable as well. And that's with a 0.4mm nozzle.
So , yeah if you get it right you can print pretty small and detailed parts.
But do it in mm :-)