Nord theme settings for nextcloud. Requires custom css plugin. Copy paste values under 'Settings > Theming'.
Work in progress tho, doing this along the way when working with nextcloud.
Apparently, there are actually people taking a look from time to time. Thing is, I don't use Nextcloud anymore (at least at the moment). So yeah, if you find colours in a real ugly aqua tone, just either fix it yourself or drop a short issue and I'll apply it. Tyvm, peace out.