This is not Termux:API wrapper, but rather a wrapper for ffmpeg and termux-camera-photo. If you wish to work on this, please implement a video recorder backend for Termux:API application first.

No. It is not a wrapper for termux-camera-photo. It uses termux-api not termux-camera-photo

Doesn't matter, idea is the same: it still uses Photo for making Video. Only from that side it is not eligible to be a part of termux-api scripts. It doesn't represent the video API but attempts to poorly implement it through ffmpeg and sequence of frames obtained through CameraPhoto.

Is there a simple way to do this on device in Termux, specifically Android 10+?

No, you will need to write a Java class that implements a simple video recorder. Considering the issues you have linked previously, possibly that besides recorder you will need to implement an option that will allow video streaming on selected port.

This would not be an easy task.

Please note the script name termux-camera-record not termux-video-record.

Video is anway recorded with camera, isn't it? Yes, you can create it from the images, but that doesn't change anything. So don't play with words.

If you want to contribute, please make sure your changes do not contradict the project design. I understand that implementing video API through Java is difficult, but no one forces you to do so.

This BASH script is not a video recorder even though it produces video output as a final result at present. Its intent is to store camera output that the user can access later

Why you have linked issues (termux/termux-api#360, termux/termux-app#981) that require implementation realtime video? Your solution is not realtime and even not close to it. Framerate also suffers - I'm about delays between images and not about ffmpeg tricks.