Module development and code questions

The tick box  "View the administration theme" is not available on the drupal 9.01 permissions page. I've looked at a couple of instances on my localhost dev and can't find it, searched a couple of databases and can't find it.
Am I missing something or is it not available?

I created a page in a custom module. I want only the current user to access this page on their behalf.

For example, I am using it with ID 51. If I go to :

/user/51/tasks

I can see this page.

If I go on :

/user/78/tasks

I must have an error 403 access denied.

How to do this ?

I created a custom module for Drupal 8.9

I have the Drupal Commerce and Group modules.

I want to create 3 pages and use TWIG templates :

• /user/ID/tasks
• /srore/ID/tasks
• /group/ID/tasks

I want to create a template by type of group and store. How can I do this ?

My module is certainly full of errors.

With my code, the pages are well created, but the TWIG is not rendered.

task_notify.routing.yml

In the snippet below, I'm trying to get all of the donations content type for the current page so I can iterate over some information on each of them.  However, when I use var_dump on the array containing all of these donations that I want, it shows an array with 57 donations, when I only have 3.  

Presumably, it is no coincidence that the first 54 donations look like this:

[0]=> array(3) { 
  ["target_id"]=> string(2) "25" 
  ["_attributes"]=> array(0) { } 
  ["_loaded"]=> bool(false) 
}

and the last 3 look like:

I created a page view with a context filter to allow only current users who can administer their account to see this page (the screenshot).

I prefer to create a custom module to rewrite the view. But when I go to my page, I get a 403 error.

What's wrong with my permission ?

enter image description here

task_notify.routing.yml

I just started a custom module (Drupal 8.9) and I use the following modules on my site :

https://www.drupal.org/project/commerce

https://www.drupal.org/project/group

How to create 3 pages in 3 different entity: