bookshelf/desktop FR speakers with decent sensitivity?

The general trend has been significant improvement in Class D, with some performing very well now. But there are also still many cheap, questionable ones out there. Reading a lot of reviews of real-world users of the exact thing you're interested in from the exact supplier is usually a good idea.

Last time I looked, Hypex and ICEpower were still at the top with regards to quality in the more accessible segment of the market, but that was a couple years ago, so I'm not sure if there are any others that are consistently good now. Purifi is also getting good press, but I don't think they have any lower power/lower priced options.
At the risk of repetition, just to add my 2cents worth over the past decade plus I‘ve owned a range of ClassD amps from low powered Tripath Kingrex T20, Sure 4@100w (yeah, with a stiff tail-wind😉), Topping TP30, Hypex UCD, and ICEpower 200AS. As Matt notes substantial improvement to the sonics of this class of amps has been achieved over the past few years, but it’s still a matter of implementation; just scroll through the numerous reviews by Randy at cheapaudioman - even the same device can vary significantly depending on other factors - sound familiar?
I guess it’s also a matter of application and expectation; in my own case desktop meant something that sounded better than a $100 pair of powered “computer“ speaker, great for casual YouTube viewing but certainly not for critical monitoring/mastering of audio-video mixing that some folks do. I quite liked the combination of the TP30 (better sounding DAC than whatever was on my former office PC‘S soundcard) and Fostex FF85WK.
Any of the current 5 -6 cm class of Mark Audio full range drivers would also bear consideration - none of which require huge cabinets.

Horses for courses.
 
These are Chris’. Made by Bernie.My work on the driver.

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dave