Internet on pixl.js

I am presenting at the fair and I would like to include Pixl.js.
I need bidirectional communication/websocket between pixl and the web app.
I have Android phone with mobile data (wifi, BT, BLE).
I can also use RaspPi 4 using EspruinoHub (BT)? Or ESP32 dev board (serial or BT)?
What would be the easiest option?

The easiest is probably to wire an ESP8266 to the Pixl.js and connect to the WiFi directly? https://www.espruino.com/arduino-esp8266

Websockets may be possible too (https://www.espruino.com/ws) - I'm not sure if I've tried that on a Pixl, but I'm pretty sure you won't be able to get HTTPS, just HTTP

ESP8266 looks good.
So MQTT would be a better option? https://www.espruino.com/tinyMQTT
Thanks!

I think either should be ok - maybe give the websocket example on that page a try first and see how it works?

So I got mention Arduino ESP8266 board.
Can I connect it directly/pins to pixl.js without soldering? How? All DIP switches to off (closer to numbers?) and use Debug Port TXD/RXD?
I would like to power both boards using CR2032 battery. How?
How do I verify if ESP8266 has an appropriate firmware?

Any additional info and pictures would be much appreciated.
Thank you.

All the information you need for connection, including pictures, is on https://www.espruino.com/arduino-esp8266

Can I connect it directly/pins to pixl.js without soldering? How

From https://www.espruino.com/arduino-esp8266#using-as-is

• Ensure SW1 and SW2 are OFF
  
• Connect a jumper lead from the TXD pin on Debug Port to D0 on the Arduino header
  
• Connect a jumper lead from the RXD pin on Debug Port to D1 on the Arduino header
  
  

I would like to power both boards using CR2032 battery. How?

It's not possible I'm afraid. A CR2032 doesn't provide enough voltage or power for the ESP8266.

You'd need to use at minimum a Lithium Ion battery, but maybe the easiest is just to use a USB power bank?