not sure about pledging, but reciting brochos in shul would be appropriate. MO do it for Israel and IDF, I know some shuls do it for US President and some for US Army, but I don’t think it is wide-spread. All old sidurim have that. I have two that daven for the opposite sides of WW1: Austrian Emperor and Russian Czar. I presume they had to publish those and also say it. I don;;t know whether masses supported it.
Now it could be a great time to ask Hashem to give wisdom to our government…