Does every Tor browser show the same fonts? That's whats important.

It doesn't matter really, one can write any words on a webpage, but show me the proof e.g. an unique and permanent resulting fingerprint.

I see from topics like this that many people don't understand fingerprinting, just showing a fingerprint, a soft of ID means nothing. A fingerprint must be:

1. Unique for a particular browser instance, or at least effectively rare. For example, when the same browser on different distros shows different fingerprints.
2. Permanent, the same each time you launch the browser.

how much of the internet is unusable with js disabled

Quite a lot actually. A lot of articles / blogs / news sites are actually more usable without javascript than with, because none of the annoying popups and shit can load. I suggest having two browser profiles: one with javascript enabled by default, and one with javascript disabled. So for things like online shopping, you'd open the js profile. And for things where you expect to do a lot of reading, use the nojs profile. Ublock origin also lets you temporarily enable/disable js for a particular website pretty easily.

Don't bother https://noscriptfingerprint.com/

There's also TLS-based fingerprinting which cloudflare uses to great success, no html/css/js even needed for that.

I haven't taken measurements, but there are many problematic sites these days. Lots of web developers fail to see the problems that javascript imposes on users, so they build web apps even when they're serving static content, where a regular web site (perhaps with javascript enhancements that aren't mandatory) would do just fine.

I selectively enable first-party scripts on a handful of sites that I regularly use and mostly trust (or at least tolerate). Many others can be read without scripts using Firefox Reader View. I generally ignore the rest, and look elsewhere for whatever information I'm after.

I'm running Brave and Librewolf from flatpak. Nope, it doesn't help, at least with default sandbox settings.

I would not count on it, since it's required for proper theme integration. A quick search confirms my suspicion: some font direcories are mapped.

I quite like the idea though, sort of a lite qubes or unmodified VM for all Firefox Flatpak users could be nice.

Flatpak is not a container and should not be thought of as such for security/privacy purposes:

In general though we try to avoid using the term container when speaking about Flatpak as it tends to cause comparisons with Docker and rkt, comparisons which quickly stop making technical sense due to the very different problem spaces these technologies try to address. And thus we prefer using the term sandboxing.

https://flatpak.org/faq/#Is_Flatpak_a_container_technology_

It can provide container-like functions if specifically configured for that, but that's not normal and it shouldn't be relied on as a security barrier.

I feel like on Tor specifically, disabled JS is far more common than on clearnet connections so not as big of an issue.

easy, disable css too (text browsers do this) :)

No script lets you individually allow js on certain sites, even specific sources. Block all by default, allow safe sites or temporarily allow other sites based on need. I started doing that this year and it hasn't been nearly as much trouble as I thought it would be.

I'm slowly starting to agree with @ssm that safeguarding against fingerprinting is an exercise in futility though...QubesOS sounds like something that might help though, since it makes it easy to browse from a virtual machine with fonts and other settings that may be leaked set to the most bog-standard defaults.

On a related note, disabling javascript can actually improve your user experience quite a lot for certain types of tasks. A lot of news/blogs/article-style websites nowadays are actually more usable without javascript, because you don't have to waste time closing all of the ads and cookie popups. I have a separate browser profile with js disabled and use it quite a lot.

Tor has noscript automatically enabled no?

There's three security settings via NoScript in Tor browser. The default has JS enabled.

It does, but you have to manually configure it to turn off javascript entirely.

It should, but I guess this user disabled it. I visited the same site with javascript disabled and it can't fingerprint it (not in tor browser, I don't trust it (css has nasty fingerprinting capabilities, huge mozilla codebase), I use w3m with torsocks and my useragent set to tor browsers, also tested qutebrowser with js disabled).