What is the best practice for defining regions for resources with creating a marketplace managed application?

The end-user will choose the region in which to create the managed resource group when purchasing a marketplace offer.

As a publisher, I can control what regions are available to select via the createUiDefinition file, but I ran across an interesting problem in my testing of PostgresDB Flexible Servers. The resource may be generally available in a region, but there may be quotas or capacity limitation, all of which are dynamic and change over time. Similarly, Ai Foundry models are limited to a subset of regions.

My commercial managed application is to include both AI Foundry models and PostgresDB Flexible server. The regions where both are currently available are limited and none of those regions are in Canada, for example.

I have created virtual networks in my template, across several regions, and peered them together. I have used nested templates to be able to specify the regions needed and avoid the validation errors that fail if a region is hardcoded in the main template.

None of this seems sustainable. It is foreseeable that my template will fail to deploy in the future if the capacity to deploy the database in the region I have specified goes down to zero.

Is there a mechanism to dynamically search, identity, and filter (by country ideally) regional resource availability within the ARM template and assign regions dynamically within my nested templates?