Here's a short template for contacting merchants who already accept Bitcoin but don't accept Monero yet:
I notice that you accept Bitcoin as payment for your services. Increasingly, merchants whose customers care about privacy accept payments and donations in Monero (XMR). Monero offers strong privacy protections by default.
There are many ways to accept Monero, including direct acceptance, BTCPayServer, GloBee, and NOWPayments (which also can convert to an EUR bank account for settlement).
Thank you for your time, and please do not hesitate to ask if you have questions. Adding support for Monero isn't just you adding any other coin; it's the world's most used private payment option.
Gist link: https://gist.github.com/SamsungGalaxyPlayer/e337f7ad5f684c82ca2009ea574a18f3