3rd House Stellium People
Perhaps its a good thing your stellium doesn't cover the 2nd-3rd houses (like mine, 4-planets).... you'd enjoy talking about yourself!!
I have a Sagittarius stellium in the 3rd house, Jupiter included. The cusp is Scorpio. I'm very quiet and observant at first (observant I'm all the time:)), but once I get comfortable I start to talk a lot and I talk about maaaany topics. I also release stress talking and it really does me good, but I don't feel comfortable talking about myself and showing too much of myself with people - unless I spend a lot of time with them and get to know them better. With Pluto in the first house even my Libra Rising cools off.
My Mercury is the 12 house, I sometimes feel that only music can express the depth of certain feelings. Also visual arts. I like to talk a lot, but for certain feelings I can't seem to find the words to define/ describe them.
I have a friend with Sun, Jupiter and Mercury conjunct in Capricorn 3rd H.
She can talk straight for an hour without a beat! She talks well, knows everything about everything and also broadcasts info on a sort of newsletter, feeling that people should know about her chosen subects. Its all very political, scientific (Covid), sometimes cultural.
I think she absolutly needs to share, and she also takes this a a duty, to enlighten people. And since she's always right it must be great for her ego!