N sized bearings

But isn’t putting the lube in the bearing an playing the lathering and scrubbing? So you only had to rinse and repeat.

Just saying that response (or lack of) is primarily in the bearing lube (or lack of).
You can make the YYJ narrow bearing play unresponsive just by cleaning it and not lubing.

Is there a way Side Effects could be altered to allow for an N-sized bearing?

No. The width is a lot wider, so you’d be better off if you could find a way to make new ones. However, I’m not sure about the post/inner diameter differences between an A and C sized bearing. Seeing as how the inner diameter of a C/N bearing is 6.35mm and the A bearing is 5mm, I think you’d need to modify the post as well.

doesn’t the 888x have a slim bearing and a full size C featuring long and short axles.

Same axles.

A lot of yo-yos come with different sized bearings (Slim C (n) and C) and don’t have different length axles.

They wouldn’t include 2 different bearings if you had to switch axles. People will strip and do other stuff and most likely complain.

It comes with 2 bearings, and one axle and a SPARE, not a different sized one…