Workflow: is there a way to edit directly from my SSD?

Yes, it works fine.

Many of us keep our original photos on one or more external drives that are much larger than the capacity we could afford as internal storage on our Macs.

Lightroom Classic has no problem working this way. If you add photos from more than one volume,  Lightroom Classic lists each volume as its own top-level heading in the Folders panel. Then you can expand the folder tree under any or all of those volumes. This also means you can run a search or filter and it can look through all cataloged volumes.

If any of the cataloged volumes are disconnected, that’s OK, the catalog remembers the paths to their photos. Those photos can still be found in the catalog, and to continue editing them, just plug in the drive they’re on.

Yes, ​@dj_paige, answer is absolutely correct. But, let me add one other suggestion: the need to back up your photos and catalog to a separate hard drive.

You’ve probably heard that there are two kinds of hard drive users. Those who've had a hard drive crash and those who've not had a hard drive crash YET.

Over the years (since the late 70s), I’ve had several hard drives crash and lost stuff. I’ve lost data only the first time. Here's what I now do:

I have a 4 TB drive that holds my images and many documents. I use a 2nd 4TB drive to back up my first drive. I manually do this at least once a week or more often if I've done a lot of work. (If you have a Mac system, I can strongly recommend Chronosync for this backup strategy. I’m sorry, I cannot make a similar recommendation for PCs. Regardless, look for backup software that can update your new data as opposed to constantly replacing all your data — it’s much faster.)

I use a 3rd 4TB drive for Apple's Time Machine. I do not know if PCs have such a process built in.

I also use a cloud service in case the house burns down. Am I paranoid? No, I’m just a realist. In a worst-case scenario, I would not lose much, at worst, sometimes a bit more than I'd like, but nothing horrendous.

[Note: the 4TB is entirely based on what I need. Your needs may demand more or less hard drive space. Whatever you think you need, double it. Oh, the backup drives, you do not need SSDs or anything fancy or fast, just reliable. Be aware that your first backup will take a long time.]

Yes, Lightroom Classic works fine from photos on the External SSD. When you import the photos, in the Import dialog box on the right under “Destination”, pick the External SSD drive and any folder on that drive you want to use.