I didn't know either but I like the 3-hour relaxing music video that was recommended to them. After a few minutes of that I thought, "How bad could they be?"
1. Telegram chat bot from this rust crate: https://crates.io/crates/telegram-bot
2. Some web microservices that the chatbot communicates with
3. Pi hole adblocking.
This is all on one 3b+ with plenty of resources to spare.