This is one of the sad situations when an executor who has issues with family members is chosen. It’s especially troubling when a son or daughter is kept from saying their farewells.
You do need to have closure so that you can move on. Try a virtual visit. Imagine your dad is there in front of you and tell him whatever it is you need to say.
If you have questions you wish he would have answered while alive, try asking anyway in your virtual visit.
Then imagine what he would have answered based on how you knew him—imagine what you think he would have answered.
I discuss all this in detail in the article, along with additional ideas for closure. Review it carefully and give it a chance.