Bridal Shower?

Graciously accept their offer. It's impolite to decline. It's only a couple hours so have fun and get your new home stocked.

"No" is a complete sentence.

Don't give them an invite list, don't tell them your availability, and repeatedly say "no".

If they try to surprise you, leave.

I disagree with this. It's fine to decline an offer to throw you a party, if you don't want a party. It's too bad they are not listening to you and they don't seem to understand that this isn't something you would enjoy. They are your family and they should know you! I don't really know what else you could say to make them hear you, but I would make sure you are being really clear about your wishes, instead of trying to hint or beat around the bush.

Sometimes we forget that it's OK to set boundaries so we try to soften our language too much...and then we end up getting trampled.

I hear you on the lack of family boundaries. But here's the thing about boundaries: you have to set them for yourself, to protect yourself. But merely setting them is no guarantee of changing anyone else's behavior. The "magic" happens when you set them and then reinforce them with consequences (which are usually in the form of reducing or cutting contact).

I sincerely wish you good luck. I did not want a bridal shower for myself and I would have been really upset to be surprised with or bullied into having one. Because this seems to go way deeper than any one party, I would not capitulate. Set and maintain your boundaries now and reap the rewards for the rest of your life.

I think your family has good intensions. It seems like they just want you to feel special, so personally, I would let them throw me a party. But if you are just insistent that you don't want one, just tell them you don't want one and will not be happy if you're thrown a surprise shower. If they throw you one without you knowing, simply leave the party - that will likely show your seriousness with boundaries.