The only thing that would be unencrypted is the system restore partition.
It uses secure boot and it’s pretty darn decent at detecting any form of tampering.
TPM 2.0 isn’t particularly resilient against physical key extraction attacks but believe it or Microsoft did threat model this…
I tried a few non-hardware exploits, even CVE-2022-41099 about WinRE but to no avail.
I’m not a security pro, but I assume once it is in recovery mode lockout you’re pretty much out of luck. From what I can tell most other exploits require it to be unlocked in the first place. Even the hardware hacks seem to require a drive being in a non-lockdown state in order to sniff things during boot.
That NVMe drive is just a keepsake now. I plan to frame it and put it on my wall as a memento.
My threat model is a lost or stolen device or RMA/repair.
If someone wants my data so badly that they’ll be able get into my OneDrive account that is protected with a passkey or a 32 char password + MFA and also have physical access to my devices let them have it.
Anyone who is that determined and capable can always resort to rubber hose cryptography and I want none of that in my life.
That hasn't been my experience. All the recent laptops I've owned (Dell and HP) had a default secure boot setup that allowed booting to Ubuntu and Fedora without disabling Secure Boot. In fact, nowadays even Ventoy works with Secure Boot [0], and I've managed to use it with the setting enabled on all machines I've tested, however in this case you might need to enroll the keys on the first boot, which I imagine will trigger BitLocker.
Apparently what happened is that Microsoft now signs some third party certs for common Linux distributions, and some setups allow these to boot by default. However, it also looks like Microsoft wants these certs disabled by default [1], which should improve BitLocker integrity on average.
Although I believe what happened in OP's situation was that BitLocker wasn't actually enabled or working, likely due to misconfiguration or lack of any.
[0]: https://www.ventoy.net/en/doc_secure.html
[1]: https://www.omglinux.com/boot-linux-modern-lenovo-thinkpads-...