What are the choices out there for monetization using ads outside of using google ads?

I use https://www.buysellads.com at www.startupcosts.co having a ~6% conversion rate.
Pays its bills and then some. :)

Facebook Audience Network is also good.

PubGalaxy have worked quite well for us, I’d recommend looking at them. Another couple that might be worth a look that sit in our ad stack - www.tribalfusion.com and www.pulsepoint.com

If your market is tech-oriented, Carbon Ads is nice. They work with sites like Laravel, Dribbble, Coding Horror (the blog of the Stack Overflow and Discourse founder), JSFiddle, etc. and have a generally better design than most other ad platforms I've seen.

I am not using any paid ads. Just tested lots of free strategies and using only those which worked well for me )) Paid ads are like a shot in the dark... just my point of view

I tried crypto mining - it's completely unfeasible.

We are trying reddit cpc campaigns, so far no conversions but at least you are not paying for adblocked impressions.

Propellerads. I tried them for a short time they do popunder ads and they're a bit spammy tbh.