As far as I can tell, it only blocks things when attached to a network. Binding/Unbinding, controlling remote prints, etc. The SD card to move files works just fine. It doesn't "know" there is an update unless you connect and bind it to a Bambu account, so you are fine to keep transferring the "old fashioned" way.
How do I know? I have multiple printers at the high school I work at, and all of them continue to work. We cant use LAN mode or cloud printing, due to IT restrictions on the network (some of district's IT restrictions are hella dumb, but that is another conversation...). All of them have continued to work fine. I have to "hotspot" my phone to get the printers onto a network to download updates, so some are running the original firmware they shipped with.
If Bambu goes out of business, the slicer will continue to work with Windows 10 and 11. The printer will still be able to print. You may lose some of the fancy controls (Bambu Handy app, etc), but saying "It will brick" is a vast overstatement.
Bambu gets nothing from me or the students whose prints I make. It doesn't talk to the server at all. And for those who are concerned about the data going to Chinese servers, that has been fairly debunked (NA servers use AWS, nothing connected with China). The only "evidence" I ever saw on that was either fear-mongering, or people posting AI summaries without actual data to back it up.
@Ryan , how exactly did it "brick" yours? Or do you mean that it removed the ability to do things across the network you used to be able to do? If you disconnect it from the network, will SD printing still work? Just trying to get more details.
I am not saying Bambu's corporate policy is amazing. Not saying they are without fault. But calling it "e-waste" and "giant paper-weights" simply because they block unauthorized use of the network seems a bit too broad. They still work just fine. Do you have access to all the functionality? No, but that is different than saying it won't work AT ALL.