For the collective spending it would be more interesting for Wallet to allow the payer (the one who paid, for example, for dinner) to request a specific sum from people in a group, either making it evenly split, or adjusting the amounts for every user in the chat (having the option, of course, to select only the people in the group who actually went to dinner), so that every single user find it easier to pay back the friend by simply clicking the button in the group chat.

For the custom mute time, I believe that can be easily replace by most smartphones with the built-in custom-time "Do not disturb" feature, which would mostly mute *all of the notifications* instead of only Telegram (or else I would need to manually custom-mute chats in every app I have on the phone).

I see qhat you mean with the Do Not Disturb feature and I agree, I didn't think about that. Perhaps it would be useful to have a mute on folders, but why not just a complete hide feature when on mute?
In the scenario you proposed, you might be working and have some work-related chats on Telegram, but then, if using your proposed feature of mute folder, the folder would still appear and could maybe distract while you try to focus on the work chats. My idea is to maybe make it an option to also sort of "archive" the folder for the time in which it is muted, so the whole Telegram UI becomes a work (or else) focused environment, where all you can access is all you need. It can be implemented in different ways, like from a top-bar button if you enable it in TG settings, but it can start with your Folder Mute feature.
In Android I believe it is called "Focus Mode", where the apps you select become unavailable until you deactivate it.