That’s an option, https://linuxphoneapps.org/apps/dev.geopjr.archives/ can also read zim files, but I’ve found it to be a bit clunky - still, I recommend giving it a try.

See https://linuxphoneapps.org/categories/conference-companion/ - both Confy and Kongress are decent. And then there’s a relict from N900 times: https://flathub.org/en/apps/at.priv.toastfreeware.ConfClerk

The color picker unfortunately is a wider issue, it’s a standard component of IIRC libadwaita that’s just used in Gajim.

This is great, even if at least one app in that collection is only available for x86_64, which makes it hard to actually run on a phone ;-) They also updated the Device Support section of metainfo guidelines: https://docs.flathub.org/docs/for-app-authors/metainfo-guidelines/#device-support . Looks like some apps on the KDE side still need proper metainfo to show up: https://invent.kde.org/teams/flathub/issues/-/issues/34