Citation needed. I'm pretty sure all Chromebooks have a TPM and it's a firm requirement for making one. ChromeOS uses the TPM extensively and fully supports remote attestation:

https://www.chromium.org/developers/design-documents/tpm-usa...

TPMs have been a requirement on PCs since at least 2016 I think, and in reality most came with them before that too (but there's a v1 vs v2 difference).

> a 1.X version of the TPM. In theory it performs just as well as TPM 2.X but they will not be supported because, again, I will not be able to use my own keys.

This is all wrong. TPM 1.2 uses SHA1 for everything which is a broken hash function so there is a major difference in robustness between them. That's why TPM 1.2 is being phased out. It has nothing to do with "using your own keys" which is out of the domain of what TPMs do anyway, TPMs are always owned by the device user. You're thinking of firmware boot signing and other things that are separate to the TPM chip but even there, you can use your own signing keys.