Looking for Vendors or Tools to Build a Comprehensive List of Civil Defense Law Firms and Partners in the USA

Question for folks about vendors, resources for building a list of target ideal customer profile firms and individuals. I have a very targeted ICP (civil defense side law firms) and individuals (partners and managing partners at those firms). I am looking to build a comprehensive list of all the firms and individuals in the USA who fit this profile to do cold outreach via email and phone, as well as targetted social media advertising. We have Apollo.io and it has been helpful to identify portions of this population but is far from exhaustive (when we manually search for example a city for the firms and individuals we are looking for we come up with a lot more firms and individuals). Linkedin has some of this information but so far struggled to use Ai tools since they have limited access to LinkedIn due to closed loop system. So I am looking for either a tool, or a vendor who can help me build this comprehensive list. My estimate is it around 25k firms and 250k individuals in the USA. Curious if anyone has done stuff with claude cowork, or other similar AI tool, or if there is a different solution/vendor that could do this for me. Likely would need to do some scraping of local google results or other things.