Poetry is one of the better options, but its nonstandard pyproject.toml is not ideal. PDM is basically Poetry, with the metadata standard in place, and with support for __pypackages__.
I would like to add that PDM also supports having multiple dependencies groups, and the developer is superfast at fixing issues.
It's not really solved if you have no choice but to work with codebases that don't use Poetry (quite common). There's 14 tools for people to choose from that aren't going away any time soon.
Poetry is one of the worst modern solutions to python packaging, either pick hatch or PDM, they both have more and better implemented features plus their codebases aren't a complete mess