Thank you for the feedback! If you’d like to know how the keys are generated, you can view the code below. BTCapsule uses the python-bitcoin-utils library, so all the information is there.
The receiver wallet is stored in a folder, and can be moved or duplicated to any storage device. You can buy a few flash drives and copy the folder to each one, and then after a few years, copy them to new flash drives or whatever storage options are available in the future. The receiver wallet is not as important as the sender wallet, because it’s impossible to get the Bitcoin before the timelock expires.
I will say that I don’t recommend timelocking the Bitcoin for longer than a few years. If the original owner is still alive, they can always sweep their Bitcoin before the timelock expires, and create new wallets for their heirs.
Here is the code to show how the keys are generated:
https://github.com/karask/python-bitcoin-utils/blob/master/bitcoinutils/keys.py