1 of 7

Of course it is possible, from man awk :

command | getline [var] Run command piping the output either into $0 or var, as above, and RT.

So (Watch the quoting!):

find . | awk '/txt$/{"wc -l <" $NF " | cut -f1" | getline nl; print nl }'

Please note that the command executed is

wc -l <file

To avoid the filename printing of wc.

That works for older awk versions also.
Remember to avoid the printing of a dot . with find ., that makes the code fail as a dot is a directory and wc can not use that.

Or either, avoid the use of dot values:

find . | awk '/txt$/ && $NF!="." {"wc -l <" $NF " | cut -f1" | getline nl; print nl }'