I don't understand the TP thing. You need to dry up with TP anyways.
I certainly don't want an integrated seat that gets filthy with splash back when somebody takes a dump. I can understand the wands more, but still they risk getting very dirty from various users with various skill levels. We use wet wipes which is not ideal ecologically, but a bidet risks being far dirtier than a shopping cart handle and we conserve elsewhere.
I had a Toto washlet installed on a toilet for around 15 months. When I uninstalled it, I was prepared for the worst, but it was fine underneath. You just clean the seat and lid like any other toilet, with paper towels and some kind of spray cleaner, it's fine.
What you just described is an issue with every toilet seat... it is not unique to bidets.
What I think you mean is that the sprayer/nozzle can get dirty? Do you have similar fears of your kitchen/bathroom faucet? because there's no way anything can stay in the spray nozzle of a bidet. that part self cleans instantaneously.
I don't try to clean myself with my toilet seat. It might "self clean" with water, but that is far from sterile. And yes of course a sink used to wash after using the toilet is dirty, as are the towels used to dry your hands. After a year of a pandemic, we should know that none of this is perfect. As in many cultures, we use separate towels for hand wiping and face wiping for this very reason.
I certainly don't want an integrated seat that gets filthy with splash back when somebody takes a dump. I can understand the wands more, but still they risk getting very dirty from various users with various skill levels. We use wet wipes which is not ideal ecologically, but a bidet risks being far dirtier than a shopping cart handle and we conserve elsewhere.