Another little data point - I plan to switch my homebrew router from Ubuntu 12.04 to Devuan some time this summer.
Problem is, its an Atom D2500 which may or may not be 64 bit. The CPU supposedly is, but it appears a lot of motherboards don't offer whatever is needed.
On the desktop CPU side, 64 bit support has been in everything since forever, but on the low power side... I'm not so sure.