I will often buy books on kobo because it's really easy to do so and it supports the authors, but I always download a corresponding DRM free epub eventually because I want a personal library that will still work in 10 years.
When I see something like Kindle or Audible, the first thing I do is check to see if I can strip off the DRM. If I'm buying it, I have the right to use it anyway I see fit (short of copying and redistributing...obviously).
I still check the DRM-free places first, because they deserve the sale, even if the price is higher. If I can't, I'll buy it and strip the DRM off (super simple, with the right software). If that won't work, I'll check the darknet. If there's a decent copy there, then I'll buy the useless DRM work (so the author gets paid), and use the darknet copy for my library.
Technically, this probably breaks several US laws. But I don't think any lawyer wants to try a case where I paid for the books/audiobooks, then removed their DRM. Kinda hard to show damages, or bad intent.
https://www.kobo.com/ww/en/p/drm-free
Your current best bet IMO is just to search for books that have this line on their description page:
https://www.kobo.com/us/en/ebook/shadow-claw
> At the Publisher's request, this title is being sold without Digital Rights Management Software (DRM) applied.
You could turn that into your search engine filter, i.e.:
https://duckduckgo.com/?q=%22without+Digital+Rights+Manageme...
But admittedly that's not a great way to search.
Your better option is just to make note of some publishers that do not use DRM (like Tor Publishing), and search against them instead.