Not sure about your first question. Maybe create your own fork and regularly rebase it? Guix will not be very happy with that I think, but it should work.

To pass --no-substitutes, you can pass it to guix-daemon, or remove the authorized keys from /etc/guix/acl. The second option lets you download substitutes for fixed output derivations (basically source tarballs), so it's easier in case some of those tarballs disappear from their original location.

I think the first option is selectable from the installer, but I might be wrong. Otherwise, stop guix-daemon from herd and run it manually with your options.

Le 29 mars 2021 15:05:08 GMT-04:00, Charles Direg <carloshujara@gmail.com> a écrit :
> Dear,
>
>How can I modify the flags that any program is compiled with within
>guix? That
>is, I can allow in the gnu-build-system to modify it globally so that I
>can
>add the build flags to any package, for example, add the flags -O2
>-march=native -mtune=native so global as I already mentioned, so that
>these
>are added to each package at the time of compilation, this would not be
>within the guix development environment, because what I want is that
>this
>compilation is natively for my pc.
>
>As a second question, how could I set the --no-susbtitutes option when
>installing the guix system from ISO, since I would like all installed
>packages to be compiled natively first?
>
>I really appreciate your kind time and I look forward to your
>responses.
>
>Sincerely,
>~ Abraham Huerta