No-code tool for creating API shims?

At Fivetran we frequently get requests for connecting to sources that we don't support and may not ever support, like your own API that you are the only user of. We'd like to build a connector to:

- A no-code tool

- That's powerful enough to pull data from arbitrary APIs

- Accessible to semi-technical users (analysts who know SQL)

These analysts would then use this no-code tool to create "shims" that connect Fivetran to arbitrary data sources. Is there something out there that fits the bill?