Ok so from the DecaWave you have different devices for different purposes… But yes you have documentation and API library that you can attach to you project and then develop you own solution.
I acquired the MDEK1001 kit that brings 12 devices and i developd my on localization system for my testings. Keep in mind that the decawave has a firmware to load on thesse boards and using the documentation you can see that you can implement an easy solution to test out the uwb technology.
Offcourse there are another technologies/brands like POZYX with less documentation but you can take a look too. Even POZYX uses the decawave uwb module.
So, as you can see, if you want something more suitable to your needs (having more control) you probaly need to develop in C code fallowing the ss_twr_simple exmple. If you only need to test out the uwb localization the solution that decawave offers could be sufficient.