The world below Shortwave
I'd guess many if not most of us started out as Shortwave Listeners and some later became Hams. That combined with simple AM Broadcast listening made us less knowledgeable about what's below 530 KHz other than LWBC. It's surely changed over the years but currently there's NDB, DGPS, and NAVTEX that dominate 200-530 KHz while there's WWVB, DCF77, and submarine stuff like NAA etc. lower.
The KiwiSDR does a great job down there, you just need the right antenna and in some cases a filter to overcome overload from MW BC stations.
I use a Pixel (NowDXEng) Loop and my Homebrew Notch filters for the MW OV issue. The use of the notches allows full coverage 9-30 KHz full all users whereas the 530 LPF approach limits MW and SW.
Where to listen?
Bill Hepburn's pages are a good resource, for example
To date I have logged over 400 stations below 530 KHz including about 300 NDB, 20 DGPS and after just starting on NAVTEX, about 15 there.
I use my ears and the Morse on NDB, SpecLab for the DGPS, and the kiwi extension for NAVTEX.