So, experimenting just now, if you use a FirefoxOS style UA string:
It will serve you the most recent mobile site with messages accessible in the top right. Unfortunately, with this UA google generally wants to serve you old style HTML everywhere. You may view this as a bonus.
With a KaiOS style UA string:
It will serve you the _old_ facebook site (messages in the middle of the top bar). Google will serve you a more modern view (in search and gmail).
Code:
Mozilla/5.0 (Mobile; rv:26.0) Gecko/83.0 Firefox/83.0
It will serve you the most recent mobile site with messages accessible in the top right. Unfortunately, with this UA google generally wants to serve you old style HTML everywhere. You may view this as a bonus.
With a KaiOS style UA string:
Code:
Mozilla/5.0 (Mobile; rv:26.0) Gecko/83.0 Firefox/83.0 KaiOS/2.6
It will serve you the _old_ facebook site (messages in the middle of the top bar). Google will serve you a more modern view (in search and gmail).