I mean the GPS satellites are in medium earth orbit so most LEO satellites receive the signal more or less the same way as people a few hundred km further down,

I mean the GPS satellites are in medium earth orbit so most LEO satellites receive the signal more or less the same way as people a few hundred km further down, no? The comms between the GPS satellites and the ground stations is pretty interesting, see figure A4-1 in this for what happens to accuracy over time if the satellites stop getting corrections from the ground: https://navcen.uscg.gov/sites/default/files/pdf/gps/geninfo/2020SPSPerformanceStandardFINAL.pdf https://navcen.uscg.gov/sites/default/files/pdf/gps/geninfo/...