As ambiverts , we have no problem making friends with both introverts and extroverts because our personalities are compatible. The truth is that we can identify with both the extroverted and the introverted aspects of our friends' personalities and are content with our social circle while also appreciating their need for solitude. https://introvertmeaning.com/ambivert-vs-omnivert-powerful-guide-to-know-what-are-you/
But we all have a little bit of each type within us. So the answer to the question "Are omniverts rare?" is no. People aren't all introverts or all extroverts, but they aren't the same either way. To know more about omnivert or omniversion, visit Introvert Meaning.