Hey,

Check out the advertising formats offered by Cointraffic: https://cointraffic.io/advertisers/ad-formats/

You can run Banner and Native Ads, together with Press Release distribution service.

As mentioned before, it will be hard to pick a Telegram group with real users and views, so using bot-free ads might become a solution for you.
If you have any questions, please feel free to send me a message or contact us using the Live chat.