I wonder if you can still use the old magsafe power cords to charge the new machines, even if at a lower wattage. Those charger cables aren't cheap, and I still have a few from old MBPs.
You can keep using them with a Magsafe-to-USB-C adapter, for example from Elecjet [1]. I have a couple of those and they have worked just fine with my 2017 MBP.
I highly doubt it, MagSafe 1 to 2 looks similar but are different physical dimensions. MagSafe 3 looks to be the same, the port looks significantly skinnier/shorter than 2 (about the same as the usb-c ports).
