I've worked at a few .. there's one that immediately comes to mind from your description, but some are much better than others at giving freedom to their staff to pursue their own ideas.
There is funding like LDRD which is meant to support ideas from the bottom up.
I’ve previously worked at one before and have since drifted away from basic research. At this point I am gravitating toward it again... in your opinion, what FFRDCs are best at providing that freedom / are less political?
My friend just started a job at LBNL and is loving it. LLNL is considered a great place to work as well. I can't speak to every single lab but I hear good things about working at both of them.
There is funding like LDRD which is meant to support ideas from the bottom up.