The chat platforms roughly break into 3 groups:

• Chat Apps Hate All Bots
  • Whatsapp, Signal, Facebook Messenger
  • This is the realm of adversarial interoperation, where you'll need to run some bridging software or something that someone else has built as well as dodging rate-limits and bot detection alarms.
• Centralised Chat Platforms Allow Some Bots and Tools
  • Slack, Discord, Telegram
  • These have APIs and bot tokens that you sign up for and work through the documentation, occasionally finding that what you want to do needs to be adjusted to fit their model of interaction
• Self-host and Create Whatever You Want
  • Rocketchat, Matrix, IRC, Nextcloud Talk, Mattermost
  • Getting the software up and running can be a pain, but once it's up you have maximum freedom. Read the docs to understand the domain, then build your dreams

The annoying part is you don't usually get to choose which platform you're working with. If you do get the opportunity to choose, think carefully about what you'd like to have further down the line.