In Ansible. This might be a bit of a challenge. I have this variable:

nodes:
  - name: fin
    hosts: 2
  - name: swe
    hosts: 1

And from this I would like a fact like this:

fin:
   - name: fin1
   - name: fin2
swe:
   - name: swe1

Is this possible?

There are multiple solutions. I'll give two which are the easiest and most legible and maintainable in my opinion.

Use a custom filter

This is my preferred one as using python to transform the data gives much more possibilities. I just crafted one which fulfills your above requirement. Meanwhile note it is not production ready as you should add input data validation and exception handling. But this will give you the global idea.

Create a filter_plugins/my_node_plugins.py file adjacent to you playbook:

def transform_my_nodes(nodes):
    transformed_nodes = {}
    for node in nodes:
        node_list = []
        for node_number in range(1, node["hosts"] + 1):
            node_list.append({"name": f"{node['name']}{node_number}"})
        transformed_nodes[node["name"]] = node_list

    return transformed_nodes

class FilterModule(object):

    def filters(self):
        return {
            'transform_my_nodes': transform_my_nodes,
        }

Then the following playbook:

- hosts: localhost
  gather_facts: false

  vars:
    nodes:
      - name: fin
        hosts: 2
      - name: swe
        hosts: 1

  tasks:
    - name: Transform data with a custom filter
      debug:
        var: nodes | transform_my_nodes

gives:

$ ansible-playbook transform_with_filter.yml 

PLAY [localhost] *********************************************************************************************************************************************************************************************************************

TASK [Transform data with a custom filter] *******************************************************************************************************************************************************************************************
ok: [localhost] => {
    "nodes | transform_my_nodes": {
        "fin": [
            {
                "name": "fin1"
            },
            {
                "name": "fin2"
            }
        ],
        "swe": [
            {
                "name": "swe1"
            }
        ]
    }
}

PLAY RECAP ***************************************************************************************************************************************************************************************************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Use a template

Create a templates/transform_nodes.j2 file adjacent to your playbook:

{% for node in nodes %}
{{ node.name }}:
{%  for node_number in range(1, node.hosts + 1) %}
    - name: {{ node.name }}{{ node_number }}
{% endfor %}
{% endfor %}

Then the following playbook:

- hosts: localhost
  gather_facts: false

  vars:
    nodes:
      - name: fin
        hosts: 2
      - name: swe
        hosts: 1

  tasks:
    - name: Transform data with a template
      debug:
        var: lookup('template', 'transform_nodes.j2') | from_yaml

gives:

$ ansible-playbook transform_with_template.yml 

PLAY [localhost] *********************************************************************************************************************************************************************************************************************

TASK [Transform data with a template] ************************************************************************************************************************************************************************************************
ok: [localhost] => {
    "lookup('template', 'transform_nodes.j2') | from_yaml": {
        "fin": [
            {
                "name": "fin1"
            },
            {
                "name": "fin2"
            }
        ],
        "swe": [
            {
                "name": "swe1"
            }
        ]
    }
}

PLAY RECAP ***************************************************************************************************************************************************************************************************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0