Nethserver is based on CentOS and can be installed on CentOS images provided by VPS providers, see installation docs.
On NethServer, Collabora is installed to make document editing possible with Nextcloud but both run on the same host.
The Nextcloud app provides a settings page to connect to Collabora.
I assume your business platform has something like this too.
You may install Nethserver with Collabora (fast way to setup Collabora) on your Interserver test VPS and allow the loolwsd service to be accessed from the green network.
Then enter the hostname in your app settings and maybe it just works.
Code server: phabricator or gitea.
You may use Nextcloud to store Documents.
Which database server do you want to use?
As regards future of Nethserver and CentOS there are already some discussions: