I haven't dug in to to much on what we can and cant do but on our test server 1 of the mods pointed out the Forum View on Mobile is not as compact as V4 and V4 is a bit larger in Font Size. This could be partially the Site notification for being offline was up top creating an even smaller view 🤷 but, Possibly an idea would be to have different settings in Theme Manager that would be for mobile. Allowing for a more compact view setting?

Id have to look and compare to see if I would suggest more mobile view settings so maybe it's not really worth the effort.

However, is this something that could be done in a Application?

Look at https://invisioncommunity.com/forums/topic/481519-compact-mobile-table-view-for-forum-index/#comment-2991222

thanks..almost there or better, be nice too have the last poster profile image show like version 4. ill have to dig in and see.