Hi - I just joined the community to raise pretty much this feature request. My name is Doug Rinckes and I'm the founder and lead of the plus code project within Google.
My suggested feature, is very simple:
Display the plus code, in addition to the lat/lng/altitude/accuracy, after location steps (GPS/Manual) in ODK Collect.
This has come from groups who are doing voter registration. They would like to see the plus code in ODK Collect, because it means they can inform people of their plus code immediately.
This conversion will depend on adding in the plus code library. It won't make network calls, and this means it will work offline. (Offline support is really important!)
This will not change the data that the form will send - it is only a UI change, because I don't want to break the existing flow or add complexity to the processing, or add a whole new set of location type questions.
If a group wants to convert lat/lngs to plus codes after the forms have been submitted, there are a variety of tools to enable that in our GitHub project including a Google Sheets plug in.
I think we can find people to help with the coding, but looking for some discussion first!