Enable sorting the app icons from the personal settings. The order will be saved for each user individually. Administrators can define a custom default order.
Go to the Admin settings > Additional settings and drag the icons under App order.
You can easily let Nextcloud redirect your user to the first app in their personal order by changing the following parameter in your config/config.php:
'defaultapp' => 'apporder',
Users will now get redirected to the first app of the default order or to the first app of the user order.
git clone https://github.com/juliushaertl/apporder.git