I'm need need for a dropdown to show all Microsoft 365 groups in my tenant?
The pre-built Groups connector will let you access all groups you own or are a member of. However, if you truly need all groups on the tenant then you have to go to the Graph API: https://graph.microsoft.com/v1.0/groups
You can use a Power Automate flow to bring the names of the groups into your app for your dropdown.
Hope that helps,
Bryan