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.

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. [1]: https://elecjet.com/products/anywatt-magsafe https://elecjet.com/products/anywatt-magsafe