Dare i even say switching to graphql and onboarding developers to graphql is a much more resource intensive process than adding another endpoint (or a couple).
As a BE/remote I basically taught myself most of elixir's graphQL framework in a day (wait, that was yesterday), while under feature pressure (due this afternoon), mostly by poking around and doing a bit of TDD. There are parts that I really hate about graphQL, but overall I consider it a win.
Instead of doing a simple GET /a/b/1/c and presenting that data structure, they now need to define a query, think about what resources to pull into that query etc. If the query ends up being slow, they have to understand why and work on more complex changes than simply asking the BE team for a smaller response with a few query params.
We quickly realized that expecting them to learn our data model and how to use it efficiently would be much more complicated than exposing every plausible use-case explicitly. We could do this on the "API front-end" by building a set of high-level utilities that would embed the GraphQL queries, but that would essentially double much of the work being done in the front-end (and more than double if some customers want to use Python scripting while others want JS and others want TCL or Perl).
So, we decided that the best place to expose those high-level abstractions is exactly the REST API, where it is maximally re-usable.
Most API teams will give you all the resources that you need.
It is most likely the case that the FE team will ask not for more, but rather, for less.
This was the exact problem why GraphQl was created in the first place - to account for Facebook's mobile platform, because they were receiving way too much data that needed to be trimmed because they didn't want to be sending like 500kb of json over mobile networks.
Competent API teams will give you all the resources that you need to be productive as a FE engineer, and if it is the case that your data needs some trimming, then go ahead and ask your decoupled backend team, while you can go ahead and keep working asynchronously while they get that done for you.
Not Fatal as you think it is.