Vim license is charityware, if you thing the software is useful please donate to third party where help are needed. Bram essentially never ask any money.
Meanwhile, NeoVim take the Vim code, change the license, and make the donate/sponsor me. Me, me, me.
My rule of thumbs is if its more than three characters capitalize only the first letter. So, given your example I would write activateSms and smsPermission.
The key is consistency.