Most developers I know are at the far-end of development practices (one of the ERPs I integrate has tables like `F0001, F0002, ...` and fields `F00001, F00002`), and this ERPs then uses old tools like Cobol, Fox, (Old) Delphi, (OLD) VB where it has a better UI history.
And it causes to be very hard to build an API (you can't image how much torture is when an ERP vendor says "we have an API!" instead of using plain text or direct SQL)
For this, you need people that know how to do good APIs. And the good API for an ERP is NOT Rest, GraphQL, JSON, ... (ideally, you need a DB!)