This paper presents an end to end solution towards authenticated positioning using only Galileo E1B signal by utilizing the Open Service Navigation Message Authentication (OSNMA). One of the primary objectives of this work is to offer a complete OSNMA-based authenticated position solution by releasing FGI-GSRx-v2.1.0 (an open-source software-defined multi-constellation GNSS receiver) update. The idea is to bridge the gap between two open-source implementations by Finnish Geospatial Research Institute (FGI): FGI-GSRx and FGI-OSNMA (an open-source Python software package). FGI-GSRx-v2.1.0 utilizes FGI-OSNMA as an OSNMA computation engine to generate the authentication events with the information whether a tag is valid or not. FGI-GSRx compute the position authentication on the navigation layer for the Galileo signal that is OSNMA verified and have C/N_0 greater than 30 dB-Hz. OSNMA-based position authentication is presented through the findings from two real-world open sky use cases: a clean signal and a spoofed signal recorded during the Jammertest 2023 in Andøya, Norway. The results show the availability of authenticated position for 80.86% for clean signal and 10% for the spoofed scenario during the complete simulation interval. A comparison of authenticated versus non-authenticated position solutions presents high deviation of 3DRMS, mean and standard deviations of not authenticated solution which is indicative of change from the stationary true reference in case of a spoofing event in open sky.