Is there a way to print last line of a file then first line of a file in awk only?

Just save the first line to a variable

awk 'NR==1 {first = $0} END {print; print first}' file

Ex. given file as

line 1
line 2
line 3
line 4
line 5

then

$ awk 'NR==1 {first = $0} END {print; print first}' file
line 5
line 1