should I continue interviewing after verbally accepting an offer?
And you made a good point when you said,
I've been reading up and it seems like a verbal offer isn't really an offer until it's a contract
Ultimately, in a black and white world, that's basically true. Until you have a signed contract, you should continue to pursue options.
However, practically, that may play out differently in different scenarios. In some cultures/industries/areas, it's not common to ever get a signed contract - the closest you may get is an offer letter, which is usually not even legally binding - so in a sense, it's really no different than a verbal offer.
If the verbal offer contained enough detail that you are 100% sure you are interested, and you're able to quickly get at least some degree of confirmation in some written form (an offer letter, or email, etc), then it may be time to commit and take yourself off the market.
However, if the verbal offer was very high level - it didn't include the full benefits package, or it was otherwise a "rough" offer, then you should absolutely continue pursuing other opportunities until you feel that you have a firm, and detailed, commitment from a given employer.