Lots of companies. Anyone that contracts for or sells stuff to FedGov loooves having ex-Fed employees because they know the system and can work with it much better.
Yes. I could turn around on 01 OCT (if my resignation is accepted) and work for the current contractor that supports my program. 100% remote, and a higher salary. If I wanted or needed to continue working....and/or if asked to do so. My dad (was a tech writer for Navy weapons systems for years) did this after he retired civil service...started working for a defense contractor.