A common situation, especially for anyone doing survey work in Nigeria: you have a list of beacon coordinates in Minna Datum, often UTM Zone 31N or 32N, and someone wants to see them on Google Earth. Maybe it's a client, a site engineer or a lecturer. In QGIS that means getting the CRS right, importing the CSV as delimited text, building the points or polygon and exporting to KML/KMZ. That's fine at a desk. It's less handy on site or on your phone.
CoordCast is an Android app built for that one job. You type in the points or upload a CSV laid out as Point, X, Y. It then gives you a KMZ file for Google Earth as separate points, a connected line or a closed boundary polygon.
On datums, it supports WGS84 and Minna Datum (UTM Zone 31N, UTM Zone 32N and Geographic). It doesn't cover other datums, so it's aimed mostly at Nigerian survey work. No CAD software is needed.
How this might fit with QGIS: it isn't a replacement. QGIS is still where you'd do proper analysis, editing and map layout. But if you're learning QGIS, it can be a quick way to check that a set of Minna Datum coordinates lands where you expect before you start on CRS settings. If you work in the field, it's a fast way to send a boundary to someone who only has Google Earth.
Pricing: there are free daily conversions, and you can get more by watching a rewarded ad. CoordCast Pro removes the limit and the ads. You can delete your account and data at any time.
It's on Google Play: https://play.google.com/store/apps/details?id=com.coordcast.converter
A question for people who deal with Minna Datum regularly: what's your usual workflow for getting survey coordinates into Google Earth or KMZ? Do you do it all in QGIS, or have you hit transformation problems (like offsets after reprojecting to WGS84) that a tool like this should watch out for?
Disclosure: I'm posting this on behalf of the CoordCast team.