Power ISA includes an endianness switch in the spec. Power and Power64 are all BE and LE. Most Linux distros only support modern versions on LE though. Debian has a BE port but it's not considered a primary release target.
The last PPC64 release of Ubuntu was 16.04 which is now out of support by about a month. Even on that, the two major web browsers didn't support building on the platform for a long time.
Yes, it can be done if you want enough to do it.
https://catfox.life/2018/11/03/clearing-confusion-regarding-... for more info
