Tell us what you think of its bonsai potential.
there's no scale to judge the size so a little hard to assess.
I see no real taper. Looks like the first opportunity for pruning for taper is relatively high = big bonsai? Pruning off big branches close together leaves a very large scar that will take years to heal.
Pruning lower leaves a large stump with no taper and a huge cut.
What species is this? While many ficus just laugh at trunk chops and root reduction F. benjamina doe not react as well and may refuse to back bud.I believe that many potted ficus and landscape plants are F. benjamina but could also be F. microcarpa which I believe reacts a bit better.
Some thing to consider:
Soil is always a lot harder than it looks. Allow for twice the time and 3 or 4 times the anticipated effort. Cutting those last few anchor roots right under the trunk takes some gymnastics and twice the effort of cutting all the laterals right round.
Trees, even stumps are much heavier than they look. Get rid of as much dirt as you can to save injury while moving the stump. Most trees can survive bare root collection.
Work out where you think would be a good distance out from the trunk then halve that and dig way closer to the trunk. you will usually just end up pruning those longer roots anyway so save a lot of effort moving soil and dig close in the first place.
Trees seem to expand once the soil is removed. Allow double anticipated sized box to pot into.
Most trees that seemed really good in the field seem to get very plain, often downright ugly in the days following collection. Often even worse after a year or so. If in doubt pass.
Ultimately it will be up to you whether to dig or not.
As future bonsai material I have to say don't bother.
Always look for a little angle change close to the roots or at least some taper.
Strait trunks with no taper require large cuts close to the base that need many years to heal.
On the positive side you could say every stump has potential, if given enough time.
I think that every tree dug or collected is a good experience that teaches us what to do or not to in future digs.
You may find a good looking root spread at the base that deserves time and effort with any luck.
You could always take it, put it in a pot and use it to make air layers on the branches....... That's what I would do if I had infinite space in the garden.