This paper presents the latest achievements concerning 3GPP Release-17 adjacent band coexistence simulation work on 5G New Radio Non-Terrestrial Networks (NTNs) for satellite communications. For the first time, 3GPP considered the introduction of Mobile Satellite Service (MSS) frequency bands for 3GPP User Equipment (UE) direct connectivity with satellites and had to consider the coexistence in adjacent bands with Terrestrial Networks (TNs). This paper will further explain the most challenging and the main surprising outcomes of this work, which opened new market opportunities for both terrestrial and non-terrestrial stakeholders. The main conclusions can be summarized as (1) NTN UE can reuse the current requirements of the TN UE, (2) the satellite connectivity does not require a dedicated satellite waveform, and (3) TN can co-exist with NTN on adjacent channels with relaxed ACIR requirements for the tested simulation scenario.