Newsletter sponsorships vs paid partnerships—what am I missing?

I've been running my paid newsletter for about a year and I keep getting two kinds of inbound: people who want to sponsor an issue, and people who want to 'partner' more deeply (co-branded content, revenue share on a product, that sort of thing). Sponsorships are simple but feel like a ceiling. Partnerships feel like they could compound, but every conversation I've had has either gone nowhere or turned into unpaid consulting. I don't know if I'm being pitched or if I'm just bad at structuring these.