It’s really not that hard.

Most of your devices are in the Apple ecosystem and when you are prompted to create a passphrase it will ask you to put it in your iCloud Keychain. Boom, now it is available across all of those

This is how it will work for most people who don’t care about security and just casually use their devices. My boomer mom does this. It’s better than the notebook full of handwritten passwords she was using.

You have chosen lastpass and a multi-ecosystem environment with windows and multiple browsers on each. You have chosen complexity and this is not a limitation of passsphrases as they have been designed for a more common use case.

I use Linux and apple. I have chosen protonpass for my vault. I just tell my OS to save the passkey there and everything works pretty well. If not, my password is right there as fallback. It’s really not that hard.