I agree with previous comments about the need of HF. I came across this interesting situation where it seems like validation could be a bit flexible. There’s this article from Arena Solutions giving an example about Band-Aid products as a Class I device.

If the band-aid did not meet the product requirement stated in the document, the company could make design alterations and the validation tests could be repeated. However, because the consequences of band-aid failure are inconsequential, the regulatory board may not need to get all the validation documentation in order to approve the product for sale. In this situation of a product belonging to a low-risk class, the company might be able to present documentation which demonstrates the product and match it with a comparable approved product.
Respectively, I think, when you are in the spot that you don’t need a validation, it’s all depending on the risks of the product in comparison with the cost of conducting HF evaluation to decide.

(This stated article is from Arena Solutions, I had trouble adding links to comments)