The tinySA-Ultra is an affordable handheld spectrum analyzer that can be purchased for around US$130 on Aliexpress and authorized resellers such as R&L Electronics in the USA.

Recently on YouTube Manahiyo has used his tinySA-Ultra, and combined it with an RF EMC probe and an Android smartphone to create an augmented reality RF display. This is useful for measuring and visualizing the RF power around electronic devices for example. The code is entirely open source and released on GitHub. 

Manahiyo has also released an identical version that works with RTL-SDR dongles on GitHub as well.

In the past we've also posted about Manahiyo's previous work, in which he implemented a very similar augmented reality project using an RTL-SDR.