After connecting the cheap 433Mhz transmitter you are able to control the NEXA protocol RF outlets similar like the GPIO pins are controlled (http://<ESP IP address>/control?cmd=GPIO,<pin>,0/1).
The plugin support: LEARN / SWITCH / GROUP / absolute DIM NEXA protocol commands and it is based on HomesEasy / NexaCtrl llibrary avialable on GITHUB: https://github.com/calle-gunnarsson/NexaCtrl
Here is the hardware wiring of 433MHz TX module - actually for testing there is need NOT to connect any antenna, works fine in 5-10m range without antenna at 5V:

Example of plugin setting in ESPEASY interface:
Controller ID set to: 199999
Tested on GPIO:12

Execute LEARN for device 1 (simple outlet/dimmer):
http://<ESP IP address>/control?cmd=nexa,learn,1,5
(the last parameter means the number of codes send in one row)
SWITCH ON device 1 / SWITCH OFF device 1:
http://<ESP IP address>/control?cmd=nexa,switch,1,1
http://<ESP IP address>/control?cmd=nexa,switch,1,0
SWITCH ON device 2 / SWITCH OFF device 2:
http://<ESP IP address>/control?cmd=nexa,switch,2,1
http://<ESP IP address>/control?cmd=nexa,switch,2,0
DIM device 1 to 50% (DIM levels: 0~15):
http://<ESP IP address>/control?cmd=nexa,dim,1,7
GROUP OF DEVICES ON/OFF- not tested YET:
http://<ESP IP address>/control?cmd=nexa,group,1,0/1
And finally the 109_NexaTX archive: http://www.qadra.sk/downloads/_P109_NexaTX.zip
And the modified NexaCtrl library: http://www.qadra.sk/downloads/NexaCtrl_QA.zip
(you need to put the NexaCtrl_QA library into the Arduino libraries folder)
I have tested the plugin with few OUTLETS and DIMMERS and works very fine

Feel free to publish my plugin on github (plugin playground) or implement it to the standard release.