If you can’t get buy-in, you can’t get buy-in. Some companies won’t allow you to write whatever you want, Lisp or otherwise. I don’t suggest writing Lisp is possible anywhere, just that it’s perfectly attainable and within one’s power to have a career of which Lisp is a significant part if you decide that should be a priority. If working at $COOL_COMPANY that only allows Python due to CTO-mandated policy is your priority, then there’s not much that can be done to accomplish that and writing Lisp.

Sometimes, also, you have to be more persuasive than “let’s use lisp it’s cool”. Implement a piece of code as a side project that solves a real problem that people care about at your company. Don’t shove it in people’s faces or rogue commit it to production. Ask people about it and have a plan to integrate it and support it. Sometimes it works. Sometimes it doesn’t.

As professional software engineers, our job is to solve technical software problems in exchange for a wage. Some of these technical problems come in the form of giant pieces of software that you’re asked to chip away at. Others come in the form of greenfield implementation work. Some are somewhere in between. Some of these projects have 2 programmers, and others 2,000. Where on these spectra you’re being paid to contribute makes a lot of difference in how much sway you have for foundational technological choices on specific projects.