Depending on what you want to do you can get good results using tmpfs ram disk in combination with a non volatile USB plugged storage. Eg: I convert some RTSP

Depending on what you want to do you can get good results using tmpfs ram disk in combination with a non volatile USB plugged storage. Eg: I convert some RTSP stream from a pi zero to HLS on a pi4 by ffmpegging the RTSP stream to HLS files in the RAM disk. I use bindfs to make this mountpoint available as a www-data folder in /home/pi/ssd/web/hls (which is actually on an USB plugged SSD) for HTML viewing in the browser. Motion triggers events, those events can be recorded from the RTSP stream or the ramdisk (holding HLS files) to the attached SSD. The HLS conversion adds a 30 second buffer so any triggers on the RTSP stream has an hls capture starting 30 seconds before the event and the SD card is never touched and I could use a spinning disk, it wouldn't be a bottleneck (but I am somehow more confident the SSD will be more stable power wise).