Another upvote here!

I'll summarize our use case here, but feel free to contact me for more info.

Our company is dived in multiple divisions. We have 1 jira instance for the entire company. This works fine, with all security measures to be configured (roles, etc) all teams have their own project(s) and nobody can access something they shouldn't.

We use separate Zendesk-instances per division. This is because in Zendesk we can't properly configure access to certain tickets. (f.e.: deny division 1 to the tickets of division 2). We receive personal data quite often in tickets, and because of regulations/GDPR we have to protect this data and need to technically deny access to those who don't need it (or allow those who do).

Therefore we can't use one Zendesk instance but have several. Please note the European regulations (GDPR) are quite new and require lots of protection of data. Also, European countries have extra rules about it.

Our second division just started with Zendesk over the summer in 2021, so we are still figuring out how to optimally use it. We now can't integrate with Jira because the other division already did. So it sucks. Workflow is now: 'type in Jira what you already got in Zendesk'.