We had the case that the journal allowed to put a full-text version only to one place, but not to platforms like ResearchGate. In this case I added a link to the full-text to the abstract field, see https://www.researchgate.net/publication/344474227.
If it's a Springer Nature journal then maybe what you have in mind is SharedIt, a service for sharing non-downloadable (read-only) link to the full text of your work, see the following link:
On some occasions, I have found useful to create a pdf document with a link to the paper and a link to the journal published version. Then I upload this pdf to the Researchgate page of the paper (maybe as a comment).