Dear Mr. Dan Howard, do you have any information regarding what armor was used by the byzantine during their last ~60 years? The only source I know on their late army is "The Late Byzantine Army: Arms and Society, 1204-1453", but I don't know if it's up to date. Would Klivanions still bem used? And wouldn't chain mail And quilted or leather armor be popular, since those were used by the late Stradiots And also by the byzantine influenced Muscovites and danubian principalities?

EDIT: I found this site:
https://byzantineoplomachia.wordpress.com/2015/08/29/the-defenders-of-constantinople-of-1453/. Do any of the members with more knowledge about byzantine military history think it's accurate?

That article is highly speculative, but the general conclusion (that Byzantine soldiers at such an extremely late date would largely have used imported Italian armour if they or their commissariat could afford anything more than padded/quilted cloth) seems to be sound.