Has anyone successfully managed to do this? I have been avoiding it as I knew it would end up being painful, and so it is proving.
I downloaded Tahoe using the command-line in the Apple support doc. I reformatted my USB flash drive, tan the Tahoe installer and selected it. It seemed to install OK (on the second attempt - the first failed and I had to reformat and start again)
If I try to restart from it using the Startup Disks option in System Settings, then it tells me I need to reinstall MacOS.
I started up whilst holding down the power button. I managed to get into the Startup Utility and change the security policy of my main HD from Full to Reduced security, which I believe is needed. However it still won't boot from it.
I also held down the power button to get to the boot menu, interacted with the grid until I found my Untitled USB drive, moved to Continue and used VO+Space to activate it, but it doesn't do anything. It could be a VO bug I suppose as the button isn't disabled but I suspect it's related to the problem I had before.
I've run first aid on my usb drive (both normal and data partitions) and it didn't seem to do anything.
So I'm not sure if this is just not something that works, or if my USB drive is knackered or if I've done something wrong.
I know the other option for trying Tahoe is to create a new partition on my HD and install there, but honestly that terrifies me. I'd rather not do anything to break my existing installation.
ChatGPT seems to think that it just isn't possible to do what I want. I also tried Gemini and it had no clue what I was on about.
I should also say that last year I installed Sonoma on this drive but never got as far as booting from it. Before doing the above, I tried this and got the same behaviour, although did not try changing the security policy before replacing it with Tahoe.