Bushy
Two bob each way in my research on that.
On the one hand there are throwaway GPS - but not for mixing it with RPT or making precision approaches.
ADS-B IN as a warning - better than nothing when away from ATC so why not a handheld non-TSO item.
But, the machine to test the ADS-B unit is actually quite expensive for the AV LAME and is needed to certify AOK. I think that is still needed when RAD conducted to ensure the tolerance accuracy.
I guess there has to be a mix of the TSO and check processes. Particularly if you are tinkering with a TSO146 GPS etc.
Take 'em out of the panel yourself? - makes sense to me but not in the current CASA regs where they are like the plumbers union that don't allow a builder to put tiles on a roof.
Need a balance - hopefully we are moving toward it even if slowly.