[devillius]

Most password managers like LastPass let you designate someone else who can retrieve your account.

Master Passwords /Keys / Encrypted USBs in sealed envelopes stored together with your will all seem like probable options.

I personally have a Master password and a USB with my private encryption keys stored securely and Google Inactive Account manager to send instructions if I don't access my account for a month.

Good luck and I would be curious to hear what you end up doing.