Notes on Monetizing an Email List

My email list just crossed the 2,000 members marker and I'm using this post as a sort of ideas doc for how I (and the IH community) can potentially monetize an email list. Please feel free to add ideas and critique mine as well; I'm still learning / in the process of exploration!

About my list
I'm a web developer and I've built a free website theme which lives in HubSpot's Asset Marketplace that HubSpot users can install to build their
website without code on HubSpot CMS using drag-and-drop.

My theme get's 300 installs per month 🤯 and with each install I get the HubSpot customer's contact info.

These customers are active HubSpot customers already paying a significant amount of $ for HubSpot and they've signaled interest in building their website on HubSpot CMS by installing my theme.

Monetization ideas (please feel free to add ideas!)

Upsell to my Paid theme
I've also build a paid version of my HubSpot website theme which has more functionality and comes with 2 hours of tech support with me. I have a drip email series running to the free theme customers highlighting paid theme functionality with CTAs to buy. I'm already converting using this method but I need to improve the entire process.

Get email list customers to buy HubSpot
Love this idea: I'm in the process of creating a series of "helpful resources" email automations (similar to IH Growth Bites) can use some of these emails to highlight HubSpot features that can help my theme customers turn their website into a lead machine. If they buy more HubSpot, HubSpot pays me: passive AF

Sell leads to other agencies
I'm already in the early stages of this: I've begun reaching out to my list and asking customers if they'd be interested in working with a HubSpot agency for SEO, PPC, Content Marketing, web dev and all the other inbound-y things. If they reply back to me I send an intro between the customer and an agency who I've vetted and charge the agency on a per referral basis.

Affiliate links
Considering recommending web design/dev related products and services in my email series eg: an email about how to use Browser Stack to test your site across all browsers and Operating Systems with a CTA to check out browserstack using an affiliate link.

AdSense on my theme demo page
Many customers on my email list will click thru to my site which I can host Adsense on and get that sweet passive income. I applied to Carbon which would be perfect for my demo - but they denied me because my website gets less than 10k hits per month :-(

In-Email ads
Got this idea from an article I read yesterday - against AdSense TOS but maybe another ad platform would allow it?

Ok gonna stop here for now - if this is an exciting topic for you let's brainstorm in the comments.

Any ideas/advice would be super appreciated!!