Like Ron said, most mobile units are purpose-built to satisfy a specific class of mission. The simplest is talking to other hams on local repeaters in your area, in which case just about anything will work. If you plan on operating outside of a local repeater net, or over longer distances, then things get complicated. Best to work with your local ham club to get support and advice. Of course, for that, you need a license.
Basically, if you intend to treat radio comms as many do long-term storage food (buy it, leave it, figure out how to use it when SHTF) then you’ll be dead in the water comms-wise post SHTF. Bottom line: Get at least a technician class ham license, then connect with the closest ham club.