Simple developer-friendly chat app for home automation

I have various small projects and home automation systems that I want to be able to invoke remotely and receive alerts from, without setting up a web server and UI. I used to use Notify17 for receiving alerts, but since this shut down I've been forced back to email, and am now looking for a solution to cover both receiving alerts and sending basic commands. These are the options I've considered already: * Pushover - Fine for receiving alerts, multiple recipients supported. No options to respond to them. * Telegram - Sending + receiving. Might be a bit heavy for my use case, and would be better not having the bot publicly accessible. Also makes managing notifications (DND etc) more difficult when also receiving human messages. * Gotify - No iOS app. Essentially what I'm looking for is an app with a chat-like UI which converts messages to a webhook, and allows me to send responses via an API. Ideally preshared key auth, no OAuth.