I do not see why not, has you say usually associated with cavalry. But gaming is all about the look of thing for me, so without or indeed with evidence to contrary I would include one, perhaps in one of the newer raised units, I would imagine the older ones would have retained the old ones, military tradition being what it is and undoubtedly was.
If you are going through hell, keep going - Winston Churchill
Yes some of the infantry definitely used dracos (especially the auxilia), although some of the legiones would have retained their eagles, and I should imagine that there were plenty of vexillae about, too.
So far all of my infantry units have dracos; I’m going to do some eagles for the legiones soon.
I gave some to my Sub-Roman infantry, and I know that Harold Godwinson likely had one at Hastings later on. The Romans just seem like they took the rules a bit more seriously than others, and I wasn’t sure if they would carry them.
I personally like the look of dracos. I plan to give them to my “veteran” infantry and give vexillum to the rest of the troops.