US Immigration from United Kingdom

First of all, hello everybody, and thank you in advance for taking the time to read some exasperated ravings from the Scottish Highlands.

I'm a 49-year-old Scot, and I've been in a relationship with my lovely American fiancee (who's 50 and lives in Kennewick, WA) since September 2017. We had been visiting each other regularly (mostly me visiting her in the US on an ESTA) between 2017 and 2019, culminating in our engagement on Christmas Eve 2019. Naturally, we started talking immediately about putting a plan into action in order to move in together, either with her moving to the UK, or me moving to the US, but the pandemic struck almost immediately after our engagement. As a result, like many people in this forum, I haven't even been able to visit her for almost a year and a half.

We had hoped that the US travel ban would be lifted sometime this summer, but with the emergence of the Indian strain of Covid in the UK, that's looking increasingly unlikely. We've continued talking every day by video messaging, though, and we've arrived at the conclusion that it will be easier for me to get a K1 visa for the US than it will for her to emigrate to the UK (for various reasons, mostly to do with her job qualifications as a licenced clinical therapist and the fact that I don't earn enough to sponsor her for a UK spousal visa). Unfortunately, there's still so much uncertainty about the direction of the pandemic that we're in a quandry about whether or not to go ahead and petition the embassy in London right now, or wait until the travel ban is lifted. Naturally, I want to get on a plane to Seattle as soon as I'm legally able to do so, but my understanding is that once a petiton has been made for a K1 visa, it's illegal to travel on an ESTA. Our current thinking is to hold off until the fall; it will be two years next January since we've been physically in the same room, so we'll have to file for a K1 before that window expires, one way or another. She can't visit me because, like a lot of people in the US, she can't get any time off work, so I have to go to her.

My question to everyone really is just: What would you do under the circumstances?