I want substack to have some kind of overall subscription where I can allocate my overall subscription spend to the newsletters, rather than having a per-newsle

I want substack to have some kind of overall subscription where I can allocate my overall subscription spend to the newsletters, rather than having a per-newsletter fee. Maybe something like Kindle's system that has some kind page-read/engagement metric against the monthly revenue pool. Maybe something where I get discounting for buying in bulk. 10 newsletters for the price of 5 a la carte or whatever, and I can allocate my "newsletter credits" at will, even switching between them. Also how can libraries and other institutions subscribe and delegate their access?