IT told me recently that I couldn’t install a piece of software because since it was open source it wasn’t secure.

These same folks will very soon be replacing software that’s worked for years with something they vibe coded last week.

To be fair it's true. And likewise closed source is also not secure.

Turn it all off, bury it in concrete, toss the concrete in a river and hurl the river into space, and maybe then IT will be happy with the security.