it's a good idea, a great way to use a case that you may not use and to employ the time during the lockdown.
It may certainly work for some, my experience is that the problems materialize afterwards.
First, you saw yourself how it is to play loud, surprisingly people play even louder than they normally do because they try to compensate for the reduction of sound. In other words the want to hear themselves.
When you play soft, keeping this under the 90db , the volume is acceptable in most situation . You would certainly improve things if you would make sure that you use a device (a phone would probably work) where you can use a microphone and headphones.
Of course the added bonus is the fact that you can playback also music .
Another problem that you will certainly run into is the fact that in a warm and humid country, you will quickly build up condensation. This may be helped by airing and letting the case open in the sun, but at some point I think that the case may start smelling.
Very well done though ( you can publish videos in an embedded form )