However, when I looked into it, I found that buying a Boox with a recent version of Android on it, meant that I could replace most of that with apps on the device itself, including borrowing DRM'd books from my local library, which is handy sometimes.
And the price difference didn't actually seem that bad, once I took into account my desire for a warm backlight. Maybe if I already owned a simpler device with that feature, I'd have hacked it instead.
Having said that, I don't have quite the same aversion to short length reading on e-ink, so I also use Pocket and even a browser (Firefox mobile with DarkMode addon in "light" mode) and so I'm probably getting more use out of that side of things for my money.
I have heard very good things about KOReader, but the standard Boox reader is also pretty great, and integrates with the device well (e.g. the default launcher lists books from that reader) so I've not had reason to try anything different.
As someone else has mentioned, the only bad thing about Boox I've found so far is that they seems to be withholding their Linux modifications. Doesn't affect me directly in practical terms at the moment, but it's the principle of the thing.
Oh remembered, one other potential bad thing, there are apparently core apps that phone home. People have workarounds involving fake VPN apps that block specific urls.