how can i extract an apk
What do you mean by extract apk?
I mean, save an application to internal storage that I have installed on my cell phone. Like this app: https://play.google.com/store/apps/details?id=com.ext.ui
With respect Google Play, apk's are doomed - they are being replaced by aab's. So an App that can extract an apk's files will in turn be doomed.
An apk is similar to a .zip file, so on the desktop you can extract the files with WinZip, BandiZip etc.
For Android, you might like to try out Taifun's extension:
Ah, I understand, but who could help me with the blocks, I mean, what would the blocks be like? Since I'm new to this, look at my application like this, the apps are shown through "list view" and when selecting, the selected apk is saved, but how are the blocks for when I select an application, it is saved to storage, that is, to my files
You asked about it not long ago and you got a ready project aia. What's the problem? Apk files are saved in app resources.
Can you give me the capture of the blocks and the two extensions please
Open the packagemanager.aia in your AppInventor and then export the blocks as images. Links to extensions are also included in the previous topic.
After clicking on packagemanager.aia, the project should download to your computer. Open your AI2 designer, click on the Projects menu and then click "Import project (aia) from my computer"
you can always do a search in the extensions directory App Inventor Extensions | Pura Vida Apps
there you could have found this link yourself