depends,

but mostly image packs from what I know are:

a.) sets pics that contains pics that would not be posted anywhere else
b.) some use it as alternative for those who doesn't want to make patreon (rarely)
c.) usually have a common theme between images in the pack
d.) they show teasers of the contents and the release date of pack
e.) payments are mostly made via paypal

as far as I know, there's no issues with selling image packs so feel free to try,
I believe end result will vary depends on pack content/theme

I think that theme would be interesting. But is it okay i sell it that i already post it everywhere

mmm not sure about that

unless its posted pics coupled with alternate versions that's not posted?

Actually i was the (b) type. Not really comfy with the patreon stuff. Kinda feel guilty when people gives money for nothing. Also I don't have something that i create monthly