Can I cast my Apple devices to ChromeCast or FireStick?

Can I cast my apple devices to Chromecast …

Apple’s own streaming protocol is AirPlay, which is different from and incompatible with Chromecast (Google Cast). However several third party iOS mobile apps support both AirPlay and Chromecast. Those apps usually feature an in-app Chromecast (Google Cast) button:

I think the Chrome browser on Mac also does some Chromecast (Google Cast) streaming.

… or Firestick?

Certain newish smart TVs with Fire OS are also AirPlay compatible.

Not external Fire TV devices though, as far as I can tell.

AirPlay 2-enabled smart TVs and third party streaming devices - Apple

iPad or iPhone? Only using third-party apps. For example https://apps.apple.com/us/app/docast-cast-and-mirror-to-tv/id6446948344