Honestly I've got 1 tree that I can tell for sure is a graft. I'm still having a hard time telling myself. So a graft is basically they have a tree or a set of trees that might be rare or hard to grow, they take and chop a branch off then they take the roots of an easier to grow and maybe sturdier root? I'm happy to get more pics of it to find out!
The nursery site says it came from Monrovia and it kind of looks like they point out when it is (at least for flowers) I searched graft on their site to see if it said anything and I found a bunch of gardenia with "(grafted to such and such)" in the product title.
Basically yes. Often it's cost and time effective to graft a mother plant rather than waiting for cuttings as with maples and many many others.
Often it is more for the sake of health or more vigour as you mention too. May or may not be a rare cultivar when grafting cultivars is applied.
So yours where it changes direction, and in a good way it does for the hobby too, appears to be a fine line just below the lowest branch.
Also the trunk appears thicker below the "graft union" at the root stock, but could just be the photo, but the trunk texture looks a bit more appealing above on the cultivar.
I have a 'Congesta' mugo grafted to a Scotts Pine, and the colour difference gives it away more than anything.
The only thing I would change on yours is the right branch that would be the 1st keeper on the right
if we are viewing the actual front of the tree, will need to be slightly kept in check over the next 3 years maybe
while the lowest left branch extends and thickens. Now would not hurt IMO to remove back to the 1st bifurcation inside
of the terminal. I mean keep the branch as long as you can, cutting back to the 1st joint you come to.
There's a knuckle there,(EDIT at the trunk) and would not hurt to also remove ONE opposite branch inside curve of the trunk.
Leave a 1/4" stub and seal. Vasoline, if no bonsai cut paste, will do.
Notice I'm not saying to do a styling. Thin the tree or anything of the like. Snip snip and watch it's water intake.
Water when it begins to dry a little more than half an inch down or so.
I have no idea what fertilizer may be in the soil. No idea how long this has been potted.
Before you decide to put it in the pond basket, be sure the soil is not falling off the root ball.
Be sure you see roots filling the sides of the pot NEXT year when you raise it out of the can.
Leave it in the can now, or if you have lifted it already, what did you see?