Simplify wifi.save() to be able to drop jswrap_wifi_restore

You mean, move it from firmware to javascript?

Well, sure it's possible, but to be honest there are more heavy part we should discuss to remove to have more free heap and figure out why the firmware has less heap with each esp-idf update.

My first test results with esp-idf 4.1 based on JumJum's work to make it happen is

sdkVersion: "v4.2-dev-521-g6fd855ab8",
freeHeap: 9924, BLE: true, Wifi: true, minHeap: 8280 }

and it is missing TLS at the moment.

Have you used EFEU? It is an online firmware build tool maintained by JumJum which allows to build a firmware with stuff you need for your project.