You should consider selling it on the Mac App Store in addition to it being open source. I think you’d be pleasantly surprised.
I think the second would be more useful and interesting. More people likely to look at it if a good discussion ensues, so you still get exposure, and useful advice from people here.
But, I didn't (and wouldn't) pay for it as a product. I did donate a coffee or two a while back, but I think in general window managers will always be a hard sell since all it takes is another bored programmer to open source a clone and you're kinda sunk. On top of that window managers have always been a free/FOSS thing, and changing that would probably require offering a feature that is so compelling people will overlook using closed source software/payware. Last, customization/scripting is a hard requirement for most window manager users, and without the source the vast majority of people will refuse to even invest the time to switch.
While I personally hate the trend, the only way to monetize would probably offer some sort of cloud based feature that requires a subscription. I think if you did it honestly, offered real value, and provided a self-hosted option for sticks in the mud (that won't give you money, but will evangelize for you if you keep things libre) you could probably carve out a decent living. Either that or offering support to enterprises who want to use your tool, but that comes with its own devils.
Anywho, just my two cents. Thanks again for all your hard work, I know it didn't pay off how you wanted financially but the tools you created have huge userbases that use your code every day hundreds of times a day. At the very least I'd hope having that on your resume has helped you find a good gig somewhere, and if not I'd suggest posting on here in a hiring thread or finding a good head hunter who can translate that experience into a well paying gig.
The other thing to think about if you make this a paid app is the price point and utility. The one thing I dislike about a lot of Mac Apps like this, which provide some simple functionality, end up discontinuing development if there isn't much revenue or if the developer gets busy. So when the OS updates or something breaks or it doesn't work with a new model/hardware changes (Ex: Touchbar), there's no support or updates. (This is something that I factor in, looking at what other things the developer has done or supported in the past, based on the price point for the app ($1 vs $10 etc)