It varies by agency — either something built in house (very bad) or built by a company that knows how to acquire government contracts, of which there are few - the set of which frankly always has worse tech than Palantir. If product efficacy is not absolutely critical, the acquisition process will be driven by nepotism or other forms of corruption.
As an example for the second case in DoD space, there’s Advana.
As an example for the second case in DoD space, there’s Advana.