InfoPath Dev

We had an Infopath browser form in SharePoint 2013 with a drop down list filled with rest api data connection. We used rest api because this dropdown list had 10000 plus items. It was completely working fine in SharePoint 2013 as a full trust admin published template. The issue started when we migrated it to SharePoint online. We made the template works in SharePoint online browser. Bust rest api data connection keeps throwing error: Error : XML data that is required for this form to function correctly cannot be found. Before taking decision on re developing the complete solution in Spfx. I wanted to hear it from the Infopath experts. Is it possible to load 10,000+ items in infopath browser form dropdown list in SharePoint online? Will rest API work in infopath form SharePoint online? Is there any other way to make this possible?

I can confirm this. I just added a SharePoint REST API connection to an InfoPath form and published to a new library. I get the same error on open. Another alternative might be to try FormsViewer - https://www.qdabra.com/en/products/qdabraForms.aspx#overview for more info. We support SharePoint REST API connections.