Yes, that's exactly what I want to do

To achieve what is required, it is necessary to have a calculated field, and configure it with the following code:

for record in self:
variable1 = record.campo_many2one_1.name if record.campo_many2one_1 else ''
variable2 = record.campo_many2one_2.name if record.campo_many2one_2 else ''
record['campo_concatenado'] = variable1 + ' - ' + variable2

Remember to replace variable1 & variable2 with a different name and also replace with the field names many2one and the calculated field

I attach a screenshot and a video of how what you require is working, within the code there is a "-" that can be modified, or if you like, tell me what the fields you have are called and I will gladly help you create the custom code you require

Screenshot:
https://ibb.co/m5PtcJN

Video:
https://watch.screencastify.com/v/VXgPf7pFSJklJxW3SoyV