I've been using a trackpad and keyboard for my iPad for a while now and in all my apps the trackpad and keyboard work perfectly except for Lightroom which annoys me a bit because its the only app actually pay for.
First off you can't zoom into photos like in the default photos app or safari using the trackpad, I've tried everything and I don't even think there is a way to zoom in using a trackpad altogether
second of all its really buggy to use generally in the whole app
it really does annoy me because its a paid app and I expect a paid app to have somewhat basic support for these things.
Another thing i would love is shortcuts. I'm not familiar with the desktop/lightroom version of Lightroom but I'm sure it has some keyboard shortcuts and it would be great to have them on ipadOS