Macbook won't boot from USB or do Internet Recovery after deleting main volume

After [encountering some errors](https://apple.stackexchange.com/questions/461796/determine-if-macbook-pro-hard-drive-is-damaged-or-repairable) with the main volume of my 2019 Macbook Pro, I deleted the volume (and, I think, recreated it), expecting to be able to reinstall MacOS on it from Recovery. (I believe there was a recovery partition there, but there's no way to check now. It's a 512 GB drive with encrypted APFS volumes.) Internet Recovery appears not to work. After entering the wi-fi password (correctly), it returns to the "Choose network" page. I have now tried using a bootable Ubuntu USB stick and a bootable Windows 10. In both cases, after holding down Option, I get to a page that looks like this: Selecting either "EFI Boot" then goes into the same "Choose network" page and doesn't get anywhere. (It's not clear whether the computer is attempting boot from one of these images, or, perhaps more likely, attempting to recover onto it). (If I don't hold down Option, we just go straight into the failed Internet Recovery path, without the "EFI Boot" options.) So...currently I can not get anything to boot in any form here. Ultimately, I would like to get to one of these situations (in decreasing order of preference): 1. Dual-boot Ubuntu/MacOS 2. Single boot Ubuntu 3. Booting Ubuntu on an external drive (ie, give up on the internal drive completely) What can I try next?