Have you looked in to a Bitkey?
They have tools to help with inheritance.
https://bitkey.build/inheritance-simplifying-the-transfer-of-bitcoin-to-future-generations/
Discussion
I generally wince at 3rd party assistance here, but I’ll go read it all and try to understand the risks. thanks
I get that.
If you do decide to go with your initial idea and are looking for simplicity rather than having them download a wallet to transmit the transaction you could simply point them to a website to broadcast such as https://mempool.space/tx/push
Another idea for you is that you might want to make the wallet that the funds are sent to be a bip-85 derived seed from your main wallet. That way if you transmit early as long as you have access to your initial wallet you are not at risk of losing funds.