It's not the sending the messages that has me stumped, it's the setup of the server (the hosting of it itself).

Do you know of a public service that exists i could build/test the Apprise plugin against? Would love just even temporary access to a server to perfect its design (then my account could be terminated)

You don't need to host a Mastodon instance yourself. Plenty of them are open for registration :)

e.g https://masto.ai/ or https://fosstodon.org

Thank you! I feel silly for asking when the answer really was right there in my face. I was able to sign up with a service. Apprise will hopefully have Mastodon support next!