Hey Katriel,
Annie from the Support Team here!
While Front doesn’t have a feature that mimics this exactly, an option I find very helpful is to collapse the left sidebar (if you’d like to read more about this feature, you can visit this Help Center article). This option allows you to focus on the inbox/section you’re currently in, without the distraction of the whole sidebar.
If this idea doesn’t quite fit your needs, you can always submit a request for it at this link. This feature submission form is linked to our Product Ideas Portal which is accessible to all users. When features are submitted, they are listed in the Ideas Portal and can be upvoted by other Front customers who may want the same feature to improve their team's workflows. You'll receive an email update if your feature is developed and shipped!
Most of the improvements you see to Front come from ideas and suggestions like yours, so thank you for making Front even better!
I hope this information is helpful!