Without trying to sound condescending, you’re basically rambling surface level half-truths about encryption, companies, legal pressure and proprietary components like IME.

Firefox Sync is open source. It gets encrypted locally. If for some reason someone is interested in your bookmarks, they won’t be able to get them from a Firefox Server. They’ll simply grab them from your local system in their unencrypted state.

Yes, most currently relevant CPUs for consumers, implement something like the IME or the AMD equivalent of it. This can be a source of paranoia, but, unless you are expecting to be the target of state actors, not a very logical one.

It honestly sounds like you read some technical keywords, looked up their definition on Wikipedia and drew your own, wrong conclusions.