Sign up for Progressier, and complete the PWABuilder instructions. At the end of the process, you'll get a packaged zip file for use at Google Play. Unzip it.

Create a Google Play Console developer account.

Load the .aab from the zip file you got at step 2 to /release/production. Create a "New Release". If the zip file doesn't contain any .aab file, check this.

Now, you need to help Google verify that you own both the Google Play app and the domain your PWA is on. In the Google Play Console, go to Setup > App Integrity and scroll to "Digital Asset Links JSON". Copy the complete JSON text file, which contains a new sha256 fingerprint for your release.

Go back to the zip file from step 2. You should find a file called assetlinks. Open it with Notepad or any other text editor. Replace the entire content with the JSON file you copied from step 5. Make sure the assetlinks file still gets saved in JSON format.

Upload the assetlinks file to yourdomain.com/.well-known/assetlinks.json. Google needs this file at this exact location with this exact name. Of course, replace yourdomain.com with your actual domain.

Now that your domain is connected with your Google Play app, follow the instructions from the Google Play console to get it released!