Do I need to use arc gis pro or desktop to prepare and publish data to a webmap for use in the collector app or can this be done solely in arc gis online?
You may not require desktop or pro if your data is in the following format. You can just use ArcGis Online to publish your data.
Comma-separated values (CSV) files that contain coordinates or addressesMicrosoft Excel files (.xlsx or .xls) that contain coordinates or addressesGoogle Sheets on Google DriveGeoJSON files or zipped shapefilesFeature collectionsZipped file geodatabasesZipped collections of georeferenced photos (photos with locations)A template or existing feature layer
Publish hosted feature layers—ArcGIS Online Help | Documentation
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