How can I sort imported images by file name in Photos on an M1 MacBook Pro?

Because Photos is a photo manager, and filenames are not what it works with. It's looking for the Title in the metadata.

However all is not lost. You can add the filenames to the Titles using an Apple script, here:

Thematic Index to Photos for Mac related … - Apple Community

for instance this one:

Script: Batch Changing the Titles to the … - Apple Community

Pictures in Photos cannot be sorted by filenames. Since they can change depending on how they are used, filenames aren't considered an important part of an image, and Photos is concerned with images. Date of capture is an important aspect of an image but, unfortunately, not when they are scanned. I have many old family pictures that I've scanned, and neither the filename nor the date is particularly useful.

Images have Dates, Keywords, Titles, and Captions, and in Photos on a Mac, you can sort by Dates or Titles. So one option you have is to use the filename for the Title. There are some user written scripts that can help with that, here:

Thematic Index to Photos for Mac related … - Apple Community

Personally, I use the 3rd Party app  Photos Workbench($30) to fix my Titles. You get lots of options, like this:

This shows the Filename plus a description, but you have many choices to include in the Title, including date, camera model, index number, etc.

There is also a Title find & replace to help fix mistakes! The app also includes the ability to compare two pictures side by side, and it can help in rating pictures.

In Photos you can push the pictures around to the order you want, and then you can use a script to change the dates, or to add dates to titles by using scripts or Photos Workbench.

Of course Yer_Man said some of the same stuff about the time I was typing…

Why on earth would Apple effectively spit in my face like that

I really wouldn't take it personally. Be honest, the real problem here is that you chose to try and solve your problem in the Finder before even testing to see if your method would work in Photos. If you'd done this work within Photos you'd have no issue. Or if you'd chosen any of a dozen photo apps like say, Graphic Converter to do the work, again you would not have this issue. So I think maybe you should be prepared to take responsibility for your own incorrect assumptions.

As you were a developer yourself, I'm sure you realise that no app is all things to all people. Photos has its target cohort of Users, and yes, they mostly shoot with iPhones or at least digital cameras, and while it will do more, that is what it's best at. Perhaps you might consider one of the many other photo manager applications and find one the works with filenames.

And certainly, if you feel Apple are abusing you so, I cannot think why you would use any of their products one moment longer.