Anything reasonably short can become a brand, They can even be spun-out once the contrived Primary term has become adopted and accepted. The difficulty is getting a major Corporation to adopt the term.
These corporations have many balances to contend with. Do they go for something recognisable with association or base-launch and spend to create recognition.
Unfortunately Spenit doesn't really evoke anything positive. yes , you could stretch it to Spendit or something similar but even this is not a great term, even in its original spelling.
You need your 'thinking head' on to have any chance. Associate first, then derive, Not the other way around.
Spedit seems to be closest associated success story and closer to speed-it, A far better association