os.symlink creates a single symlink.
ln -s creates multiple symlinks (if its last argument is a directory, and there’s more than one source). The Python equivalent is something like:
dst = args[-1]
for src in args[:-1]:
os.symlink(src, os.path.join(dst, os.path.dirname(src)))
So, how does it work when you do ln -s /home/guest/dir1/* /home/guest/dir2/? Your shell makes that work, by turning the wildcard into multiple arguments. If you were to just exec the ln command with a wildcard, it would look for a single source literally named * in /home/guest/dir1/, not all files in that directory.
The Python equivalent is something like (if you don’t mind mixing two levels together and ignoring a lot of other cases—tildes, env variables, command substitution, etc. that are possible at the shell):
dst = args[-1]
for srcglob in args[:-1]:
for src in glob.glob(srcglob):
os.symlink(src, os.path.join(dst, os.path.dirname(src)))
You can’t do that with os.symlink alone—either part of it—because it doesn’t do that. It’s like saying “I want to do the equivalent of find . -name foo using os.walk without filtering on the name.” Or, for that matter, I want to do the equivalent of ln -s /home/guest/dir1/* /home/guest/dir2/ without the shell globbing for me.”
The right answer is to use glob, or fnmatch, or os.listdir plus a regex, or whatever you prefer.
Do not use os.walk, because that does a recursive filesystem walk, so it’s not even close to shell * expansion.