Howdy Jonathan,
I recently explored options for generating .mbtiles from ESRI products and found that the easiest way to get the job done was to use QGIS. QGIS is free GIS software and has built in capacity for vector or raster mbtiles in version 3.18. I believe there are plugins that you can install to add this functionality to earlier version of QGIS.
I am still wishing that this would be possible directly within ArcGIS Pro but it was not difficult to learn the basics of QGIS for this task.
b
