Yes, you can put your Descent data into Subsurface. But, that is actually a negative point, to me. Not that you CAN put it in, but HOW you have to do it. You cannot download directly from the Descent into Subsurface. And, that is ONLY because Garmin dictated to the Subsurface developers to NOT allow it. Garmin required it to be done by downloading to Garmin and then exporting that to import into Subsurface.
I really like how easy it is to download via BT from my Predator or Teric directly into Subsurface on my phone, while I'm still out on the boat, usually. And then it is just "there" in Subsurface on my laptop when I get home, without any extra steps.
I know you meant that you can't get from the Descent to Subsurface directly via Bluetooth but the process is actually very easy, and for me it is actually easier and quicker than with my Perdix. I rarely boat dive so this may also influence my preference.
The Descent will automatically upload the dive activity to the Garmin cloud as soon as it is Bluetooth range of your phone (assuming the Garmin Connect app is open on the phone - and I mean it just has to be there in the background) and the phone has an internet connection.
I pretty much only do shore dives. With my old car, within a couple of minutes of walking back to my car, my dive activity was already uploaded to Garmin Connect. I didn't have to take any action at all. With my new car I have to turn my phone off as it acts as a key (and if I leave it on anyone could drive away of they broke it). This means I have to turn my phone on before the dive activity will upload but as I also need to turn my phone on to drive home, that's not a big deal. I usually turn my phone off just after I unlock the car so the process now is not that different.
To get the dive into Subsurface, all I have to do is go into the dive in Garmin Connect on my computer, download the zip file, unzip it and import into Subsurface. The process takes around a minute.
Of course, if I have no internet connection (or Garmin is down for maintenance or a Ransomware attack) the process is not as smooth. That said, it was very easy for me to connect my Mk1 via USB and copy the files to my computer and then load them into Subsurface.
Now, while I can (and usually do) download my dive(s) to Subsurface from my Perdix via my phone, it is very slow and requires my attention. I have to put the Perdix into Bluetooth mode, start Subsurface, connect to the Perdix and download. A single dive takes 15-30 minutes! My phone is tied up that whole time. This is not something I waste my time doing at the dive site. I usually wait until I'm busy doing something else at home and do it in the background. Note that I do it via my phone because that is quicker than either my laptop or desktop.
Of course, this is how it works for me and I appreciate others are different. While I don't see any value in having my dives visible in Garmin Connect, it is a convenient way to get them to my computer.