I made a few tutorials a long time ago, which I'm sure the process has changes so far. let me write a quick guide.
1. You need to export your project as an Android/iOS
2. your project file should essentially become an HTML5 game that needs to be "wrapped" into a native android or ios package. A long time ago Intel XDK did this just fine, but that method no longer works. You can wrap this package using free compilers, but I haven't been in the scene lately so I'm not aware on whats out at the moment. You may need to research the topic " Convert HTML5 games to APK" or to your OS' of preference.
3. sign up for a developer account for your perspective store. For google play, you can do this here
Publish your apps and games with the Google Play Console and grow your business on Google Play. Benefit from features that help you improve your app's quality, engage your audience, earn revenue, and more.
developer.android.com
When I signed up, there was a 99$ fee.
I don't know if its still the same price so please research.
For iOS
I'm fairly certain they have a yearly charge of 99$. It was a hard pass for me, so I never looked into it.
One thing to note, you MUST submit a developer address and email address. This WILL expose your address to the public. I personally went to UPS and rented a box for a while. They allowed you to use their physical address if that doesn't bother you.
4. Pretty much, its self explanatory after that. Upload your package file, describe it. Wait a few days and its up! Keep not that you do have to update the android package it was compiled with to keep up on the store. I think my benchmark is still on there. (look up RPG Maker MV Benchmark on the google play store) I think it gives a warning that the package isn't update.
Hope this helps