Creating vector pbf files for reference layers

Hello. I have customized my geopoint collector question on the kobocollect app such that the user can see the basemap while they drop their geopoint. Kobo also allows the survey creator to add a reference layer on top of the basemap that the user can see while dropping a geopoint. I have added a reference layer as a .mbtiles extension which I saved in my android sdcard/odk/layers folder. My question is that the .mbtiles reference layer is a raster tileset and I want to create a vector tileset. Kobo only allows vector pbf files created from mapbox. I have no idea how to convert my reference layer into a vector pbf file that will appear on my app. Any help please? This article allowed me to get to where I’m at now:

To reiterate: How can I convert an ordinary vector file (shp, kml, etc.) into a vector pbf file? Then download it?

I’m also interested in this, but only raster layers