Find My no longer works on my Apple TV to locate my iPhone.

Yes. You are right.

If it is that, as you said you were told, "“Find My” isn’t available for tvOS", the only other step I can suggest may be to send feedback to Apple about the issue. They will likely not reply, yet your feedback will reach those behind-the-scenes, who are able to make changes. If others are also sending feedback, we may see the issue addressed in an update.

Here's the web-form for feedback to Apple:

Feedback - Apple TV - Apple

Yeah this is annoying. I literally use this to find my iPhone all the time and all of a sudden it’s not available on the App Store. Why did this happen with no explanation? How does an entire function/app/software disappear not only from the device but also from availability catering to the device without anyone knowing anything about it?!

Hi, and welcome to the Apple (user-to-user) Community.

Re: Find My no longer works on my Apple TV to locate my iPhone.

Wondering if your Apple TV Operating System may just need updating to remain compatible.

(NB: That is ... if you do not have it set to update automatically)

About Apple TV (2nd and 3rd generation) software updates - Apple Support

Online (non-Apple) article: How to update your Apple TV ... lists the different models

https://www.macworld.com/article/672019/how-to-update-your-apple-tv-and-install-tvos-14.html

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Other things you can ask Siri on Apple TV – Apple Support

says:

"If your other Apple devices (iOS, iPadOS, watchOS, or macOS) have the

Find My feature enabled and are signed in using the same Apple ID that

your Apple TV uses, you can ask Siri to trigger an audible alert on any of these devices.

Your Apple TV and your device must be on the same network and nearby.

Note: For more information about setting up the Find My feature, see the user guide for your device and operating system".

iPhone User Guide – Apple Support

Apple TV User Guide – Apple Support

More support if needed:

Apple TV - Official Apple Support

All the best :-)

Thank you for your reply, and the added info on the tvOS.

The iPhone may also need the latest compatible iOS version.

For iPhone 8 and above, if not already updated:

About iOS 16 Updates - Apple Support says iOS 16.5 is the latest.

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Re: “Find My” in the Apple TV App Store.

Wondering if your Apple TV is set-up for downloads ok:

Eg: How to: Get your Apple ID ready for purchases or downloads on your Apple TV - Apple Support

How to: Find apps in the Apple TV App Store - Apple Support

Eg: says

"You can use Siri to dictate search requests to find apps on Apple TV."

and

"Not all features and content are available in all countries or regions."

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You maybe able to use iCloud on the internet to find your phone:

iCloud - Find My - Apple

Thank you: It is looking like you may need to use iCloud online, instead, anytime you want to find the iPhone.

Thank you!

All the best!