Its possible to avoid all of those binaries (including the Linux kernel) and build from source instead.
https://bootstrappable.org/ https://lwn.net/Articles/983340/ https://github.com/fosslinux/live-bootstrap https://stagex.tools/
https://bootstrappable.org/ https://lwn.net/Articles/983340/ https://github.com/fosslinux/live-bootstrap https://stagex.tools/
It looks like most of the time was spent discussing Python. I suspect that is because it is possible to create software without an explicit build stage, so you would not receive warnings about a dependency until the code is called. If the software treats it as an optional dependency, you may not receive any warnings. This sort of situation is by no means unique to interpreted languages. You can write a program in C, then load a library at run time. (I've never tried this sort of thing, so I don't know how the compiler handles unknown identifiers/symbols.) Heck, even the Linux kernel is expected to run "hidden packages" (i.e. the kernel has no means of tracking the origin of software you ask for it to run).
Yes, you can write software to detect when an inspected application loads external binaries. No, it is not trivial (especially if the software developer was trying to hide a dependency).
And just a quibble: even bootstrapping requires the use of a binary (unless you go to unbelievably extraordinary measures).
The Linux kernel has the IMA subsystem that is intended to prevent executing untrusted binaries, enroll all the hashes from your package manager, and then you will know where every executed binary came from. Or just verify the block device with dm-verity. Or both. I believe that similar functionality exists on Windows and some interpreters have support for asking the kernel to check if files can be executed before loading them.
https://ima-doc.readthedocs.io/en/latest/ https://www.kernel.org/doc/html/latest/admin-guide/device-ma...
The Bootstrappable Builds toolchain requires the use of machine code of course since CPUs only accept machine code, but that machine code is in hex numbers in a text file with comments and that form is considered the "source code" not "a binary", aka it is "the preferred form for modification" (the phrase used by the GPL). The human starting the bootstrap process has to review it is correct, enter it into the computer in some trustworthy way, and start it. Yes, the bootstrap process does go to unbelievably extraordinary measures :)
Except mankind uses other platforms as well, and even having the source code available isn't enough if no one is looking into it for vulnerabilities.
Windows/macOS/etc are pretty irrelevant if you don't want to trust binaries, because most of them don't come with full source code. People who care about this stuff aren't even going to consider proprietary platforms.
In any scenario where you would do a full-source bootstrap, you would be reviewing the code for each step of the process, or deciding which reviews published using crev or similar are trustworthy enough for you.