This page is just a reference of all the known Steam APIs, I do not know how they work. Please do not email me with questions.
UNDOCUMENTEDPOSTGetMobileSummary
https://api.steampowered.com/IMobileAppService/GetMobileSummary/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoGID of the mobile app's authenticator for this user
string No