Again, without knowing your specific application, it's not possible to provide much guidance. Design validation is demonstrating that your user needs and intended uses are met. Normally, these high-level requirements are elaborated in a user needs or customer requirements specification. Those are then translated into system requirements (which are verified).
Field evaluation / clinical trials are certainly one aspect of validation. Usability is also a validation consideration (see IEC 62366 or HE 75). I also consider product safety testing (IEC 60601) part of validation.
IQ, OQ, and PQ are more associated with process validation and not generally considered product validation.
To understand the complete scope of your validation needs, though, you need to know the full scope of your user needs and intended uses.
Since you posted in the CE marking forum, maybe look at the essential requirements. Those are, after all, user needs. That may not establish the full scope but will certainly need to be addressed.