Novo Nordisk's own clinical trials (OASIS 4, OASIS 1 Vs, STEP 1). In order for oral Semaglutide to be effective you need to substantially increase the oral dosages for the same effect. Meaning you need more Semaglutide for the same action-of-effect, which increases side effects (+2.6% Nausea, +6.9% Vomiting, based on 2.4mg Vs. 25mg).
As I said above, this is being worked on (inc. by Novo Nordisk), but oral Semaglutide is a very naive early attempt. They got first to market, but that doesn't mean it makes sense for people who can handle injections; you cannot compare doses 1:1 because of how weak oral is, you need to compare action-of-effect. Once you look at effectiveness, oral costs more than injection.
Source?