Connecting Figma’s remote MCP server to a third-party MCP gateway (TrueFoundry) via OAuth. Has anyone made this work?

I’m trying to connect https://mcp.figma.com/mcp to TrueFoundry’s MCP gateway using OAuth2 (Authorization Code + PKCE, DCR registration, scope mcp:connect, authorize URL https://www.figma.com/oauth/mcp).

Errors:

• Invalid scopes for app (400), when using https://www.figma.com/oauth.
• Invalid scope: mcp:connect, when using /oauth/mcp, even after re-registering the client.

A regular OAuth app from the developer portal has no MCP scope, so that route is out.

Has anyone connected Figma MCP to a gateway like this?