https://us.litelok.com/products/litelok-x3-moto
(Apologies for the all caps in the title, but that is apparently how it is branded
TL;DR: nice big lock; compatible with HPE if you remove a little rubber.
A little while ago, thinking about how to move forward locking my HPE after dealing with a couple of bike thefts, I went looking for the best lock setup I could for my apartment. During the search for something that was Sold Secure Diamond (https://www.soldsecure.com/approved-product-search?standard_grades=2&keyword=), I came across the Bennetts reviews of the X3:
https://www.bennetts.co.uk/bikesocial/reviews/products/security/motorcycle-chains-and-locks/litelok-x3-lock-review
It is pretty impressive in person. Substantial, especially when held with a regular u-lock in the other hand for comparison. It also comes with a cute little carrying case, which would be nice when storing it in the pet carrier. The lock and mechanism feel very well-made and the large key glides nicely. The keyhole also has a nice pair of little rubber flaps over it to keep the dust out, which is a nice touch and actually will really help with it being used outside in a dusty area.
As expected, I had to strip about three inches of rubber off the bars (and then wrap them with electrical tape to prevent scratching) to get it through the rear wheel, but with that modification it goes through without issue.
To pair with this lock, I got a chain to anchor it: the Oxford Best Chain, which is comical in its size and weight. Like the kind of thing that they tried to use on Sisyphus.
So far, it has been a success and easier than my last setup. More importantly, my bike has not been stolen yet! I can still see how somebody could do it, but I can no longer see how they could do it without taking some time and making quite a show of it.