Generally, donating 300 bits or more shows up on stream and will be read out loud (i.e. TTS). However Doug will turn the TTS on and off during streams so please double check if TTS is enabled before donating.
Please note that donations are a way to support the channel, not to purchase something from me. I cannot guarantee the message will be shown or read out loud or responded to. Please only donate if you're okay with that, and remember that donating is never required and should only be done if you are financially comfortable.
Twitch Bits are actually more expensive to buy on mobile devices due to Apple and Google's fees. Try purchasing bits on your PC for a better deal.