I am the Pakistani spouse but am a British citizen. So I can apply for ESTA but yes, as you said, it's not legal to apply for the adjustment by travelling there on an ESTA.
Also, I asked a question previously about travelling on the ESTA while the I-130 is pending and I've been told few people are questioned, if at all, and if you are questioned just have documents at hand that show your ties to your resident country to support your return. I will most probably try a trip at some point on the ESTA. My children are little and I would like to ease them into moving to a whole new country by making at least 1-2 visits so they're mentally prepared as to where they're headed to.
Etihad offers clearance in Abu Dhabi and then no checks at the POE in the US after that. Worst comes to worse, if I get turned away, Abu Dhabi is just 3 hours away. I can turn back 😔
Interesting what Crazy Cat has said. Will read into that.