As upgrading to 7.x is not really straight forward AND there is no stable release for 7.x yet, it would be great to see PHP 8 compatibility for the 6.x branch.

It might just be as simple as just replacing "^7.2" by "^7.2 || ^8.0" in https://github.com/deployphp/deployer/blob/6.x/composer.json

I get the focus is on 7.x but if this idea is supported I could open a PR and see what the impact on the rest of the codebase would be (if any)