woohooo good news! thanks to the awesome @joostvb and some help from @NGIZero libopaque is about to be included in #debian (and all dowstream distros, like #ubuntu, #raspian, #devuan and #kali https://ftp-master.debian.org/new/libopaque_0.99.2-1.html
it only has to pass the ftp NEW queue manual review.