I was reading on various delta update methods and technologies out there, courgette seems to be one used in chrome browser for some time now and base of chrome’s auto-updater mechanism. From OS update point of view there are few options like OSTree, but I came across casync project which is inspired by rsync+git for its features and seems to be impressing me. I also then found out that its also used in RAUC an update mechanism for embedded systems, which is well supported by OpenEmbedded/yocto based distrbutions and buildroot etc. I think if we can have a good delta solution it can be quite handy for OS updates for IOT devices out in field connected over slow links e.g GPS or Sattelite etc.
However there is a go implementation of casync called desync which is maintained version and I am told is used by Valve Steam deck to manage its updates using rauc.