send command to Puck.JS from the raspberry without Espruino Hub install

what would be the connection speed i need to set up

You shouldn't need one at all - connection speed doesn't really apply for something like Bluetooth LE.

You could look at using bluepy for Python: https://github.com/IanHarvey/bluepy

However if you're ok with JS then Noble for Node.js is probably one of the most stable BLE libraries out there. You could even use the code that the Espruino CLI tools use as a base: https://github.com/espruino/EspruinoTools/blob/gh-pages/core/serial_noble.js

But at the end of the day you need to:

• Find and connect to the device
  
• Find the service 6e400001b5a3f393e0a9e50e24dcca9e
  
• Find the characteristic 6e400002b5a3f393e0a9e50e24dcca9e on that service
  
• Write your data to it in chunks of 20 bytes at a time.
  
  

But if you just want an easy time of it, install EspruinoHub and then send an MQTT message containing your JS command to /ble/write/DEVICE_ADDRESS/nus/nus_tx