Search within one Site and cascading dropdown

I have created a Document Library named IZ in my DEMO_PowerApps sharepoint site. Here I have created 2 folders named Software Services and PLM inside both these folders I have some sub-folders, like inside Software Services there is a TeamCenter folder and some files (pdf,txt,ppt) similarly inside PLM I have created two folders Mendix and Polarion and some files uploaded.
Also I have added a new column named Tag which is a choice column with some values like: development, implementation, certification.

Now in Power Apps I want to implement a search functionality with the help of drop-downs. There will be three drop downs (might increase later based on Levels) the first drop down will show the main level folder options (like Software Services and PLM), if a user chooses any one option then in the gallery below it should display all the records in the selected folder. Then the other drop-down (2nd drop down) will show value based on the selection from the 1st one like cascading i.e if user selects Software then in other drop down it will display the sub-folders based on selection in dropdown 1 and show records as per selection in dropdown 1 and 2 . The third drop down will show all the choices in the Tag column so if user selects the any choice based on that filtering will be done.

So the user can either filter records by selecting any dropdown or any dropdowns or all 3 dropdowns as per the selection filter the records. If no value is selected then show all the values. 

- The other thing that I wanted to know is there any SharePoint through which we can access the sub-level (folders) names/information and is it possible to have different set of Choices for a folder level (like I have created a folder named Power Apps in my document library which has 4 choices for column named Tag and then there is another folder named Power Automate which has 3 choices which will be different (1 common).

Regards,
Sidhant