Duing my time as a LE trainer i picked up a couple of certifications as a baton instructor. ASP, Monadnock and Koga. All straight batons of one sort or the other. Ive also used them in the field.
None of the collapsible ones were anywhere near as effective as a standard fullsize straight stick. I carried a 29” Diamond wood Koga baton. Id MUCH rather use a good OC spray or a TASER.
Ive bent one of the Monadnock collapsable batons on a subjects leg and had almost ZERO effect. No drugs, just fighting mad.
I dont see any of the smaller batons being a good choice for EDC type CCW. Just not worth the effort to carry.
You also need to consider where a baton fits in the use of for e continuum. Its not appropriate against a firearm. Against a knife, you'd better be damn good and really lucky (even with more then a decade of serious stick training, i would not use a baton against a knife).
So you are left using a baton against an empty hand attack. In the civilian world, im not sure how that will play out. A baton has the capacity to be lethal. In LE work we use them to affect an arrest and are justified in using the force necessary.
In the civilian SD realm, its not so clear. Lets consider an empty hand attack. Guy comes at you to kick your Butt. You draw your baton and try to hit his arm, but he ducks and takes it to the side of the head (very possible). He crumples to the ground DEAD. How do you justify that use of force?
Empty hand against empty hand, is one thing. Introduce a weapon and it gets messy