If nothing else, you could open with just a Patreon or something. Basically as a way of outsourcing the "subscription revenue" implementation until such time as something direct yourself makes sense.
Please sell something business-like that people can purchase and expense.
A book, software, something. I can't quite expense patreon and others may have a similar issue. (Useful "free SaaS" where all there is is the cup of coffee button makes me sad).
My buyer won't even blink if I say that I need a $150 tool: I can just bill it to whatever project it's being used for as long as I get an invoice or a receipt or some kind of documentation. If I say that I found a free tool and I'd like to donate $10 to the author, no one will know how to do that.
I recommend saying 'Patreon' instead of 'Donate' on the site's main navigation menu! It does have a stronger effect because they'll associate it with a human being behind the screen.
You have my pittance! Your search engine is useful to me for recipes and that crazy cyberpunk network of back-alley Geocities-esque pages it's tapped into