Ok, looks like you are in paranoid phase. Blockstream or coldcard delete you data after 6 month and never been cracked. Phones are more insecure than HW, whatever way you wanna justify yourself. They cracked a trezor one with old firmware back in the days. All hardware becomes ewaste even you loved pixel lol
Discussion
Can you prove they delete your data? No. If you paid you credit card then that transaction will be for ever saved.