Can I use pipe output as a shell script argument?

You can use pipe output as a shell script argument.

Try this method:

cat text.txt | xargs -I {} ./Myscript.sh {}

Command substitution.

./Myscript.sh "$(cat text.txt)"

If you have more than one set of arguments in the file (for multiple calls), consider using xargs or parallel, e.g.

xargs -d '\n' Myscript.sh < text.txt
parallel -j4 Myscript.sh < text.txt