Use WiFi access points (AP) to determine your location. The estimated position can be overlaid on a user-supplied floor-plan. No "learning", "training" or "fingerprinting" required! For details see web page on indoor localization at https://people.csail.mit.edu/bkph/FTMRTT_app
Note: need to know where the WiFi access points are. Required: phone supporting WiFi Round Trip Time measurement a.k.a. IEEE 802.11-2016 (see
https://developer.android.com/guide/topics/connectivity/wifi-rtt#supported-phones ) Note: the Wi-Fi protocol is also known as FTM RTT or WiFi RTT.