Is there any programmatic interface to the specific schema of an account? Something like an inspector or reflection api?

You may wish to put more explanation behind this

I'm working with a team who is building an integration with NetSuite and is looking to get the entire schema for an account, complete with essentially all the records and fields, including custom fields. I'm familiar with records browser, schema browser, etc. Sounds like they have some similar functionality in Intacct or SF

The REST API has a metadata catalog which sounds like what you are after