I am working on integrating CrossRed Funder Registry database to OJS, but I am doing that for OJS3. It will enable you to save the funder name, id and grant id’s and will suggest funder names from the CrossRef database with their REST API Funder Registry - Crossref It should be ready hopefully later this month.
That is for a different database ( a Finnish one) and is connected to the Subject field, but it is very easy to change it to whatever REST API you use, for example CrossRef, and change the form field it uses.
We have to improve the OpenAire compliance so we need to add that specific metadata.
However your project is very interesting and we would like to be involved, there are other references, discussions or code repository?