Efficient way to move Jira server gadget to Jira cloud

Hi all,

I am a bit lost in the cloud documentation and need a quick guide on the general steps I have to take reusing my existing code.

I have a dashboard gadget running on Jira Server which is mostly running on client side (javascript resources), partly on server (e.g. license conditions evaluator).
The gadget is defined using plugin descriptor atlassian-plugin.xml and a gadget.xml.

I tried to understand what I can reuse for a Jira cloud environment, but I am not sure that I understood correctly the basic steps. Could someone give a rough suggestion?

Specifically I would like to understand, how I can reuse my gadget.xml:
Is reuse possible or do I need to rewrite it to make my own running appication?

Is there a any general guide on how to move a server app to cloud?

Sorry for these general questions, but answers would really help to understand the basic steps I need dive in at first.