MKS released the source code of wifi device : https://github.com/makerbase-mks/MKS-WIFI
After quick look the SD transfer code seems based on reprap one using SPI but the marlin part seems using specific pin WIFI_IO1_PIN to strigger the pins usage (Marlin/src/lcd/extui/lib/mks_ui/wifi_module.cpp) so need to check deeper
the transfert is supposed to be 100KB which is far better than the slow M28/M29 protocol

So far current implementation is limited to MKS boards (Robin (s) and TFT) so do not rush and expect a miracle in ESP3D for other boards yet

Currently compilation for ESP module failed on my side because I suspect it use DC42 esp core sources - not generic ones

I know LPC team ported DC42 sources to esp core 2.4.2 so it may be the case also for MKS - I did not checked

Even current sources are availables, there is a current lack of documentation on usage - available chinese doc is supposed to be translated to english soon but it may just be a reference. Use google translate is working FYI.

This post is for raising, I do not have any MKS Robin board to test, conclusion: no ETA for esp3d implememtation yet - a lot of things to do already and no supported hardware - but if someone want to help to add it (not just test it) - contribution is welcome