[newman8r]

https://www.reddit.com/r/RTLSDR/ is an active community

You can also search on github for active projects, https://github.com/topics/sdr is a good place to start

I also like to browse https://www.sigidwiki.com/wiki/Signal_Identification_Guide to get ideas for signals to look for

I personally use both rtl-sdr and a HackRF One. The HackRF makers have some pretty good videos on their site https://greatscottgadgets.com/sdr/

I've built a few basic radios from scratch as well, and the only reason is because the SDR makes it cheap to test and interface with whatever I make. Radio shack may be gone, but any component you could dream of is only a few days away via amazon, etc.

[8bitsrule]

Thanks to you both!