Tension between "publishable" and "motivating" research topics
I guess my advice would be, first, to get a permanent position, say on the tenure path and then get tenure. Do what you need to do to set a baseline.
Second, there is no reason why you need to make a final decision now and never review it. In the short term you could (probably should) work on stuff that gets you to tenure primarily, filling in with ideas on more interesting topics. Then, as the world becomes more secure you can morph into a situation that seems more satisfying.
Just keep notebooks of ideas as you go along, so that when you think of something &quot;interesting&quot; that might be pursued, you don't lose track of it later.
Stay flexible. Establish a base. Then move on.