No OS is 100% reliable or 100% safe. One thing is absolutely certain, if you carve lumps out of an official version and do not add items to enhance securitu, then the resultant offering cannot be safer than the base version.
Personally, I do not trust cut down versions as I have no idea what has been cut down or added.
I do not believe MS deliberately introduce unsafe features but can you say the same as a 3rd party offering?
To paraphrase your post:-
It cannot be 100% reliable. . if you wanna use it, then fine. . But do not presume it's 100% safe.
I'm with you on the 100% argument. What the user often fails to comprehend is that they are their own best first line of defence.
For the longest time I did not trust downsized versions of Windows either. Here is the pivot point at which we differ:
I DO verily believe MS deliberately introduces unsafe features so either way you take a gamble with MS OS.
1) The key logger that nobody likes to talk about that came standard with Windows 10 was (and is) an unsafe feature.
2) The RECALL feature that Windows 11 recently introduced and took back and put back and took back ... Who knows now?
3) The forced upgrades that Windows aggressively employed. Remember Windows 8?
4) The harmful consequences of deliberately introduced drivers via Windows update.
5) All the features Windows offers that needed patching or still need patching for security reasons were deliberately introduced.
Now
malicious intent is a whole different matter. I'm quite sure that all the exploits and software developed by Microsoft are done deliberately, but that isn't to say that they meant any harm. Take the key logger, for example. Wasn't this introduced so that MS could better assist the user? I'm certain that was the logic provided. It isn't logical that MS would want to harm its patrons. What I find more logical is that once cast into the role of "parenting" the Windows user MS starts to get too snoopy. Mommy wants to read junior's diary. Mommy wants to "help". Windows often has this uncanny ability of helping the user out of their own sanity and sovereignty. It is foolhardy to assume that MS doesn't want to capitalize off the user. After all, business is business.
No operating system is 100% reliable. Not Linux, not Windows, not anything. Nothing put together by humans (including AI) is 100% reliable or safe.