Your Fuji seeds will not grow Fuji apples I’m afraid.
They have been pollinated by an unknown tree...so they can only be half Fuji.
This is how new varieties are bred.
You can call the resulting trees what you want..they are your own varieties.
If you see a variety with the words Pippin or Seedling...( Cox’s Orange Pippin.....Bramley Seedling etc ) these have been bred this way.
The one problem you may have is because they are on their own roots and not grafted to a rootstock,. You will have no control over the trees size and they may be more susceptible to virus problems which the rootstocks would have protected them from.