Importance of Domain ?

Hi everyone,

I recently decided it is time to register domains for my mobile app "level app", which is a marketplace for used videogames.

So far .com and .app , my favorite domains are gone and very expensive. So I registered levelapp.gg.

.gg a good choice as a main Domain ? How important is a domain ?

Note: I am focused on the mobile app, I just want to use the website as a landing page.

Greetings