On the device in question, my options have recently come to exclude Secureblue for hardware reasons (which I won't get into since they're off topic for this discussion and the questions I have). The most secure options with which I find myself left are ChromeOS Flex and FydeOS (with a local account), which is where my questions come into play:
I'm aware that Flex is likely more secure overall if for no other reason than it being a Google product instead of a fork (I'm sure Fyde being on the LTS update schedule matters somewhat, too). Is FydeOS being based on ChromiumOS and having the option of a local account enough of a plus for privacy that it could arguably be considered a sensible alternative to Flex?