Coffee grinder can get a pill to a state where it will eventually dissolve in 7-8 mls hot water. Problem is it gums up quite a bit. It’s still pluggable, but to some it’s a little um, evocative. Effects still work.
Hmm, yeah I’d look into the solubilities of the various binders and then go from there.
You could likely reduce the bulk by stripping the skin off the pills (outer layer has 10% of the methylphenidate) and then identifying the core layer and separating that (as the bulk of the pill is inert- look for a guide online showing the layers).