Not worth discussion: this is a paid service with ridiculous limitations (for $15/mo) one gets support for 'converting' 1 API with 10 endpoints in a team of up to 2 members.
You do not pay for conversion. Transforming API specs from one format to another is totally free. But APIMatic does offer other services, like SDK Code Generation and creating API Docs Portal from any API spec format, which is what the paid tiers are for.
In fact, API Transformer is free service with support included, which I have not seen other SaaS providers doing.