This new release is missing a few things yet -- on-chain and withdraw using a LIghtning address. But give it a few weeks (?) for the remaining features still missing to be added and and any newly discovered bugs or UX issues to get resolved and then this wallet shoudl work pretty darn well for a merchant -- as a bitcoin on-chain and LN wallet that can also be used for point-of-sale.

In the interim the missing features are still available using the old site ..., classic.coinos.io

But for an online store, there's no e-commerce (i.e., shop + cart) type of capabilities in (or coming) for CoinOS. There are many other alternatives for that though.