Woozy Song <suzyw...@outlook.com> [WS]:
WS> I know these are not all equivalent and may have idiosyncracies.

You forgot the most obvious ones (since this is unix we are
talkiing about):

$ [long (or short) pipe] | sh

and

$ < myscript sh

Here are a few more exotic ones:

$ find myscript -print0 | xargs -0 sh

$ echo | parallel --pipe ./myscript

$ echo "From " | reformail -s ./myscript
# Similar tricks exist for procmail, maildrop, postfix and most other MTAs

# chroot /tmp/playground /statically_compiled_shell myscript

$ sg - some_group -c ./myscript

$ < /dev/null tpipe ./myscript

$ zip test.zip myscript; funzip test.zip | sh

$ < /dev/zero dd bs=1024 count=10 >tempfile 2>&1; \
tar -M --tape-length=1 --info-script ./myscript \
-cf /dev/null tempfile; \
rm -f tempfile

unix can be fun. The more you play with it, the more you like it...