Yes and no. There are still plenty of things that get tracked regardless of JavaScript, and disabling JavaScript is it's own mark they can track.
Do Not Track is one such request, but screen size, viewport size, language, timezone/region, whether you block ads or not, browser/engine version, and many more are all things that do get tracked without the need for JS.
All have legitimate reasons, but can also be abused by being tracked server-side.
The cover your tracks page on eff.org has some pretty good explanations for most things.
Fun fact, the reason the TOR browser launches in windowed mode is so that this viewport size tracking is less of a marker.
It does. It's yet another data point used in fingerprinting, and not many people enable it. 'tis but a single setting, but combined with everything else they can track about your browser it is effective.
In case you want to run a test to see how fingerprinting affects your browser:
In 2019, two nurses and a pharmacist questioned a Weiner order to apply a fentanyl patch on a 93-year-old woman who was already on opioids and bobbing in and out of consciousness. A nurse texted Weiner to ask whether he was sure. Weiner responded, “Tell them put it on or I will rip their lips off.” Weiner told me this was “an inside joke.”
What an article.
Federal regulators also failed to address alarming trends. An analysis of Medicare drug data shows that, from 2013 to 2020, Weiner’s volume of opioid prescriptions ranked ninth among all cancer doctors who bill the program. When it came to morphine, Weiner consistently ranked among the top five. In 2017, he prescribed more morphine than any other cancer doctor. The Centers for Medicare and Medicaid Services did not respond to questions.
[...]
If a patient wants CPR or a machine to keep them breathing, they elect to be a “full code.” Weiner, the hospital said, had a pattern of altering, without consent, a patient’s status from full code to a DNR/DNI, do not resuscitate and do not intubate.
[...]
If the residents of Helena had seen those files, they would know how Weiner built a high-volume business that billed as much as possible to public and private insurance, all the while sending numerous patients through a carousel of unnecessary and life-threatening treatments. They would have learned that the hospital had financial incentives to look away.
[...]
When I asked Weiner why the hospital would publicly accuse him of various types of malpractice but withhold its concerns about his end-of-life care, he said it’s because administrators knew what he was doing and even encouraged it.
In WhatsApp you can set custom notification sounds, I believe it even supports notification sounds on a per-contact basis. So safe to say you can do it as an app developer.
I wouldn't call "what servers/clients?" a particularly broad question. Unless you're serving the likes of Microsoft or Google, that can be very specific.
And, generally, no need to share unwanted personal details online.