Get List of users/groups with userpermission via REST


i am in a choir and we are using nextcloud as server for files, calendar etc.

Now i want to create a mobile App for learning all the names of > 50 members. Therefore i need to get the profiles including name,firstname,profileimage and groups.
Because i am running my app in the context of a user, i cant access the admin-functionallity.

Is there a way to get a list of all Users and groups via url / RestAPI to use this in a mobile App?