I use KOReader [1] on my Kobo. It supports Wallabag [2]. Wallabag offers both hosted [3] and self-hosted options. There's also a standalone kobo client for Wallabag [4]. In addition, Wallabag also supports direct import from Pocket.
It has been a while since I used Wallabag on KOReader and I have no experience using wallabako (that project wasn't around when I tried Wallabag). But seeing that you're already using KOReader, I don't expect either of them to present a challenge to you. As far as I remember, using Wallabag on KOReader, including sync was simple enough.
The only issue I have with Wallabag is that it reduces the battery supported time significantly. This isn't a big issue in my case, but a longer backup would be nice. However, others have reported that they don't suffer the problem to the same magnitude. Perhaps wallabako can reduce that power usage when KOReader can be exited.
[1] https://koreader.rocks/
[2] https://wallabag.org/
[3] https://www.wallabag.it/en
[4] https://gitlab.com/anarcat/wallabako