Previous growth leader for EMEA @Skrill, @Hootsuite and Merchantry (now @Tradeshift) Expertise in SaaS, eCommerce, Online payment and online advertisement. Board member and advisor for a series of start-ups around the globe.
Seems your strengths are in content creation and amplification of such content on social channels. This is not an easy skillset to acquire and develop and even though channels are becoming more reliant on publicity, there is a huge value to good quality organic traffic. First, anyone using ad blocker will see organic content (and only organic content). Then a lot of ad networks are recommending to put advertisement budget behind good quality content (as opposed to traditional ad messaging).
So from my point of view, you have some good assets to leverage in the market and your potential customers could gain a lot by partnering with you. From the few ideas you list, the one most closely linked to your existing expertise is Media company, where you would offer to run campaigns for not-yet-discovered creatives. The obvious challenge here, is how much budget do they have, and you will end up in a similar position as an investor, propping a few creatives that won't ever get decent recognition for hopefully supporting a few very strong ones that will carry you along with them over time. Those successful ones will have to be profitable to make up for the investment on the others.
Hope this helps!