Newpipe and Just (video) player have this function, but the former cannot play offline files and the latter cannot play audio files. I can rename the audio file to mp4 and play it in Just player, but it doesn’t have a background play option.
From what I’ve searched on the net, in both apps the feature us implemented from ExoPlayer. On F-droid, Auxio audio player mentions ExoPlayer, but does not seem to have the feature available.
Are there any foss apps that has the feature to Skip silence for audio files?
Don’t think that this is true (unless we are talking about a fork that I am not familiar with). The FAQ has an entry on this and mentions that you need to use an external player. I use mpv and VLC.