TL;DR (Sorry, I like explaining things in-depth): It's most likely just to do with your phone, if you could tell me what phone you have, that would be greatly appreciated.
That's likely to do with your phone, if you could tell me the kind of phone you have that would be greatly appreciated. I just ran a test on my budget test phone (Samsung Galaxy A01 for reference) and it took about 12 seconds on the first loading screen.
The issue is that the GLES3 renderer used in the Android port runs fine on more powerful phones, such as my high(er) end test phone (Galaxy Note 8) and my personal phone (Pixel 7a), but on cheaper phones GLES3 takes much longer to compile shaders (the Vita port taught me that, because even the GLES2 renderer takes forever to "load").
Unfortunately, you can't switch the renderers on the fly with Godot games. There is a built in argument to force GLES2, but... there isn't an easy way to use that on Android (if not impossible).