The only combat feats hagaromo has is the fight against kaguya that took a month..
He is just as much as a god as isshiki.
And yes you should need feats for a character to be called strong rest is just assumptions.
If isshiki and hagaromo where to fight it would be a close combat fight becasue Literally everything Hagormo will use or throw at Isshiki, will be made microscopic and thus completely ineffective.
Not to mention he was unable to use full power in the munk vessel...