Here's a PoC you won't like: https://phpstan.org/r/b3fa4f91-9308-492e-b4e5-b33e45242f3f

The problem you're facing is that there's no key-of for properties and that offset access type U[UKey] does not work on properties.

Basically you would have to reimplement https://github.com/phpstan/phpstan-src/blob/2.1.x/src/Type/KeyOfType.php and https://github.com/phpstan/phpstan-src/blob/2.1.x/src/Type/OffsetAccessType.php for properties, which is possible with https://phpstan.org/developing-extensions/custom-phpdoc-types.

But personally I think that having an object that allows both $row->one and $row['one'] is overcomplicated and not really necessary.