Donations (you mean tips coz you are not a charity) are provided by a third party service so no they probably are not in chat, depends on the service you use.
No that would need eventsub which you can consume via ngrok,
could do that with subscriptions too since you have ngrok…
or keep polling the API
PRIVMSG parse for the bits tag
So, since you are an extension, and using ngrok, you could use eventsub for all the things and the server that servers your extension files can server EventSub webhooks.
So your NGROK server points to the Extension server and the Extension server can also act as your EBS.
Or also put your EBS behind NGROK