Would you consider reihō a form of meditation?
Depending how involved it is, could be. I don't think a simple bow qualifies. A more intricate action in acknowledging your opponent or in starting class might reach the level of a mini meditation but IMO is too brief to get the job done.
Saho(o) more closely fits the bill as it's more involved. In iaido, there is a
ritual beginning of class where one goes into
seiza (kneel), carefully places the sword on the floor in a prescribed manner, pays respect to it and then inserts it into the obi.
Depending on how one defines "meditation" the above actions may qualify. For me, the key is,
does the action play a significant role in obtaining a mental/spiritual attitude that prepares you for the upcoming activity? Of course, the mechanical action alone has no meditative value unless one sees and uses it that way. It must be internalized and the gravitas of the situation recognized and appreciated.
For me, the iaido ritual I've described was enough for me to get my "game face" on, so to speak. By the time I wedged the sheathed sword into my obi I was in an attitude of calmness, focus and awareness, ready to safely swing sharp steel around a bunch of other people doing the same.
Some schools among the various arts do a dedicated meditation period, ranging from ten seconds to a couple of minutes, in addition to
reiho or s
aho. Personally, I never saw the benefit to me. I'm able to quickly get "into the mood" needed for class and
saho is sufficient. But it can be beneficial for others in assisting them to prepare for the task at hand.