Have you look into Withings? I know they make a fantastic scale that has an app. I just don't know about using it with voiceover. I have a regular scale and I don't like to get on it much, haha, because I have to ask my husband to read it out loud for me.

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I use the body mate body+ scale. App is the most accessible I’ve found for voiceover users, and has a good range of features.

I like qardiobase 2. I just step on it, it vibrates once, wait a little, it vibrates again. I step down from it and then the scale recognized me and uploaded the data to the app. Data is screen-reader accessible.

I have the Withings Body Cardio. It measures not just weight, but body composition and a few hearth/cardio related things. It has a big, super screen with backlight, big letters, so even with limited vision it can be seen - you haven't mentioned how much you can see.

I don't think there is any kind of voice feedback (even a beep from the scale).

Setting it up the first time to connect it to the WiFi will require vision.

When using it you get feedback from the scale only through the screen. As it measures like ten different things it may take 15-30 seconds of standing still on it (but it is worth it IMHO).

The measured data is instantly uploaded to the Withings servers and you can see it in their app or website just a few seconds afterwards.

I don't use voiceover/talkback, but the app is nice, big letters, big contrast, nicely arranged data.