Yes, those could be detected.
Ill see how large that portion is on my system in a bit, but I would expect it to come out as the minority.

Non-detectible ones I can think of rn:

• Tab muting manager
• VPN manager
• link redirect skippers
• stats printers, like a tab counter
• dynamic shortcuts, like opening the archived version of the current page on archive.org
• old reddit redirect
• cookie managers

Many more of the ones you listed won’t be detectable on most websites.

userscript managers (grease/tamper/violentmonkey etc.)

A userscript manager is by definition detectible only on pages you define or install a userscript for. Even then, modern userscript managers like tampermonkey are running scripts in a separate scope that is completely sandboxed from the actual websites js context, you can’t even pass an object or function to the website and access it there, it will fail.
Youtube has actively fought some userscripts and failed, which they probably wouldn’t have if those userscripts were detectible.

User theme managers should be similar, but I can’t comment on them as I don’t use any.

page translators

Translators are only detectible when enabled.

addons serving in-browser ads

Why would you have an addon that serves ads?

site-specific UI improvements (RES, SponsorBlock, youtube/SNS tweaks)

Are site-specific, i.e. not detectible anywhere else

privacy blockers (CanvasBlocker/JShelter/etc.)

Please don’t use those anymore, use only uBo. Same for uMatrix.
uBo is pretty good about not being detected, for obvious reasons.