Find out if a custom UI is marked as required

Dear community,

I have some troubles wrapping my head around the best strategy to find out, if my custom ui is marked as required in the field configuration.

What I understand so far:
One approach is probably to use the GET fields API and filter the response for my custom field to get the ID.

Another one could be to use the Get create issue metadata API, but in this case I need to know which project the issue is assigned/is selected (in the create issue dialog).

From here on I am confused as to where to go next.

My idea is, when accessing my custom ui (opening a modal) while editing an issue, I want to check if the custom field is marked as required and show a notice within the modal.

Thanks for any hint/direction that helps.

Best regards