We would like to assign people with a fixed percentage of their capacity to a task/project/project phase. E.g. assign Florian with 50% of his capacity (50% * 40h per week =20h per week). Assigning someone with a fixed amount of hours per week (e.g. 20 h per week) would also work.

Our intention is to do high level resource portfolio/management.

Assign people to projects, check if there is capacity for new projects,...

In our use case projects/tasks that take longer than planned will continue to consume the same amount of resources for their duration.

Please check out the example in the first screenshot. Microsoft Project. The percentage of the capacity of the assignee is highlighted in yellow.