At the risk of stating the obvious, presumably you are aware of the Osprey Book “Constantinople 1453 The End of Byzantium” which has much useful information on Byzantine troops at this time (including a decent Further Reading list of other sources) as do their MAA books “Byzantine Armies AD 1118 - 1461” and “The Varangian Guard 988 - 1453”.
I've got the Byzantine Armies 1118-1461 and Byzantine Naval forces 1261-1461 ones, but not the Constantinople/Varangian specific ones. They were honestly a pretty big inspiration with starting the project, and like you say, the "Further Reading" sections are definitely useful (it's how I became aware of the Virgil to begin with!)
That said, sometimes I think they rely a little
too heavily on icon-paintings of saints for visual references. My guess is that the armour in the icons is a sort of idealised "good old days" sort of depiction rather than a 1:1 depiction of the contemporary rank-and-file...but in the absence of evidence *against* that armour, it's still a valid interpretation! It's kind of a shame that we're stuck with very few, if any contemporary secular sources to rely on, but that's part of the challenge I guess!
