Please check joinmastodon.org for open instances. You can join any other instance and follow/message someone from this instance. It's kind of like being able to send email between a hotmail/gmail account. Here's an uninformed primer on Mastodon.

Get rid of FB, IG, birdsite, etc. and join the Fediverse. Why I quit most services that use your data in exchange for their 'free' services and alternative services you can use instead.