Hi. I suspect you’ve already answered your own question re ‘brakes/tyres’, as you lead with ‘understanding the importance of stopping’ :-)
No idea of the performance difference between the systems you mention, other than YouTube videos which favour cable actuated disc brakes (with or without hydraulic pistons).
GCN have done brake system comparisons between rim and disc brakes - you might get something from them?
I’d leave well enough alone, ride the current set up some more, and do your own tests to find out your braking distances in different conditions. This will give you an idea of whether you consider the present system is ‘safe’. You mentioned ‘don’t buy upgrades, ride up grades’, so let me give you ‘ride it ‘till you know how it rides’ :-)
Good luck!