I joined mander.xyz because it has a central theme around the natural sciences. It could possibly include STEM content as well; there is an ongoing discussion about it. The admin(s) are present and very responsive.
For anyone with a love of science and/or nature I recommend it highly as a home instance of Lemmy.
You could also get one of the SSD drives that look like flash storage. I got a “usb stick” with 512GB SSD for about $60 last year.