to add alt tags for logo and other images, go to sales channels, choose online store, click on themes and then click on customize. In the editor, on the left side, choose a section where you have the image which needs the alt text (you will have homepages selected as default). Click section and under the image, there is edit button, click the button and a pop-up will show up, where you can add the alt text.
In the left side bar, there is also a section "header", where you can add a logo and add the alt tag.
To choose other pages, just choose the one you want in the dropdown menu on the top.
As far as I'm concerned, you have to add alt tag for every product separately (this means choosing a product and add the alt text).
Hope it helped!
Images play a vital role in SEO, Which Means adding alt text may push your ranking forward. There is an idea for adding the alt text, it is to search your primary target keyword on the google search engine, where bottom you can find the related searches, insert that keyword as alt text it will be useful for ranking
we can find some