App for ECG on Apple Watch SE 2022

Apple Watch SE does not include ECG capability. There is no ECG app you can add as the watch doesn't include the sensor required. If this is a feature you want, you need to consider Apple Watch 8, which does include ECG.

You're welcome and good luck.

You can check out the Refurbished Store from Apple. I wouldn't buy a refurbished watch from anyone else, personally.

Here is a link --> Certified Refurbished Products - Apple

You're welcome. Just note that Apple discontinued the 7 Series in October 2022. You may be able to find them at Apple Resellers, but Apple hasn't sold the 7 since last fall.