QPixel doesn't have an "accept" button, no.
QPixel is a work in progress so it doesn't have everything SE has. QPixel is also a path toward Codidact, and Codidact won't have an "accept" button either.
Which answer the asker of the question likes best isn't particularly significant signal. On Stack Overflow where all of this started, an acceptance mark could be relied on to mean "I've tested this", but on more subjective sites, and these days even on SO, it doesn't necessarily mean that. Codidact doesn't want to give the asker a super-vote where it doesn't convey meaningful signal.
But wait, you might say -- we could still have acceptance, but just not let it do anything special like pin answers to the top. We could, but is the asker's opinion more important there than, say, a known expert on the subject? If I'm on SO, I probably care much more that Jon Skeet endorses an answer than that user99999 (who has only ever posted this one question) does. So, not for MVP but down the road, Codidact is talking about optional public votes or endorsements -- either a way for people to selectively make an up/downvote public, or a system of endorsements or reactions in addition to votes. We haven't worked out the details yet, but something like this would convey everything an acceptance mark does and more.
And finally, just because the asker is satisfied doesn't mean the community is. If you see a question with an accepted answer but you have a better answer, shouldn't you still post it? (And often people do, of course.) So seeing "this has been answered" on the front page doesn't actually tell you that it no longer needs input.
We want people to answer questions if they can add good new information. Acceptance is orthogonal to that.