Hi,
Well, the thing is that these are basically "things that google would like to know". It's not things that you have to provide.
For example, for the aggregateRating and review, HikaShop can provide them. But only if you activate the vote & comment system. Without votes or comment, then it's normal that you get these warnings. If you don't want to have vote & comment, then you should ignore these.
Same for the priceValidUntil. It would only be useful of you would know that your prices would change in the future and when. The goal here is that if google knows when the price will change, it can schedule when to index again your product details page to get the new price. But if you don't provide it, it will just index your pages whenever its algorithm tells it to.
Similarly, providing a brand for products made by yourself (like for example for our products on our website) makes no sense so it's better to not add it and have the warning than filling something just to have something. It's useful to fill it when it makes sense like for example if you're reselling shoes (Nike, Addidas) and the name of the shoe doesn't contain the name of the brand.
Now if you really want to remove them, you can create one custom product field per value missing, and modify the show_default.php view file to add the meta tags with the data from the custom fields. But I think you're wasting your time here and might create more problems to your SEO and work for you than anything.