Consider Alpine Linux foundation for Firefox and Chromium

[Intensity]

It looks like there's an Alpine subdirectory for Firefox, although this doesn't look like it's been updated in a while.

I'll suggest including versions of those browser images that are based upon Alpine 3.13, for sake of minimality and in order to provide viable alternatives. Supporting sound (ALSA and Pulseaudio) for these browsers would be a helpful starting point.