setfacl

I actually found something that so far does what I asked for, sharing here so anyone who runs into this issue can try out this solution:

sudo setfacl -Rdm g:www-data:rwx /var/www/pub_html
sudo setfacl -Rm g:www-data:rwx /var/www/pub_html

R is recursive, which means everything under that directory will have the rule applied to it.
d is default, which means for all future items created under that directory, have these rules apply by default. m is needed to add/modify rules.

The first command, is for new items (hence the d), the second command, is for old/existing items under the folder. Hope this helps someone out as this stuff is a bit complicated and not very intuitive.