One way of doing it would be to duplicate the sales "All documents" group and rename it (say xyz). Now, as the models of sale quotation and lead are different, you can create record rule to restrict the user to see the leads related to him/her and add this record rule to the newly created group xyz. Assign this new group to the user. As you would have duplicated All documents group, the user will be able to see all the quotations and due to record rule restriction to leads, he won't be able to see all leads/opportunities.

Edit 1 -

1> Below screenshot is the duplicate of the "All documents". In this new group, go to record rules tab and remove the record rule named "All leads". This is the first step.

2> Secondly, create a new record rule to restrict the leads to the respective salesperson. Refer the screenshot. You can create record rule by going to Settings--> Technical --> Record Rules. Give a suitable name for the rec rule, select the model as Lead/Opportunity, enter the rule definition with proper syntax (as given in the screenshot) and in group, select your newly created group. Save the rec rule.  In my case, the ID of user Mitchell Admin is 1, so i have used the same in rule definition.

3> Assign the new group to the user to whom you want the restrictions applied. My output in the below screenshots......I have applied it to Mitchell Admin

Leads restricted -

Quotations Unrestricted -

Hello, thanks for your quick answer.

First step, duplicating Sales "All documents" group is clear.  See below image. Name: All documents quotations. And already assigned to the user.

However, can you send screenshots to show me how to create the record rule to restrict the user to see his leads and how to add this record rule to the new group please? Thanks!