Narwhal

Narwhal, short for Nonvisual Android Remote Windows Handy Access for alL, is a NVDA remote Android client, allowing you to control your Windows pc from wherever you are. Since NVDA Remote is a screen reader addon without image support, this app can only be used by visually impaired persons familiar with this technology. Find out more about NVDA Remote at NVDARemote.com

To connect, configure your pc as a server and allow it to be controlled, enter the IP address, port, and key of your pc in Narwhal, then press connect. If the connection is successful, you should be automatically notified.

When you want to end the connection, press disconnect.

IN order to use the app, you need a hardware keyboard, either wireless or wired, via OTG.
If your pc is behind a router, you'll need either to forward a port, or use a relay server. See the documentation on the NVDA Remote site for instructions.

All keys are intercepted, including alt and windows. You have to enable the Narwhal service from settings\accessibility,
Some keys and key combinations, like capslock and windows key keystrokes, still make talkback speak, interferring with Narwhal speech. The only solution I've found is disabling Talkback.

if you use Narwhal with talkback, I recommend choosing the new keymap and the search key as a modifier in talkback. With the old keymap, the alt and shift keys will be trapped by talkback, meaning you won't be able to use them in Narwhal.

If using Commentary or Jieshuo, open program settings\action settings\custom hot key settings\hotkey theme settings and create a new theme with no key commands assigned, then choose it in hotkey theme. This will stop jieshuo from speaking when Narwhal is active. You can switch to a functional hotkey theme when you want to control your phone with the keyboard.

If you have too much lag, don't ask me to improve it. It is due to many factors beyond my control, including the notorious bad android latency and your internet connection. Android latency is the biggest one, try a newer phone to get better results, preferably a Pixel or Nexus. See here the android audio latency table:
https://superpowered.com/latency
The lower the latency, the better.
Also, wiFi and 4g connections are much faster than 3g.

Sending sounds, or screen video, through this app is not possible, and will never be. That's how NVDA Remote was designed. This way we have faster reaction times and less data consumption. If you need sounds, use a traditional remote control app.

Recent changes:
1.21:
pairing the bluetooth keyboard during a remote session no longer disconnects it;
updated crash report libraries;
1.20:
added support for NVDA 2019.3 and later;