Are those applications specific for Kali Linux?

Hello, everybody.

I used Kali Linux for about maybe two years. It's the first Linux Distribution that i used on a daily basis. Every time i get a new laptop, the first task was to install Linux on it.
I just got a new machine and it had malware on it. It said "Windows". Man... i decided to make a dual boot with Linux and Windows 11 and the machine was working in a really sketchy way, i deleted Windows entirely and it started working like a normal computer, it's hilarious.

Anyways, I'm just cracking jokes. So when i installed Linux a week back, i decided to go with Ubuntu. Since i never tried it and many people told me that Kali is actually difficult to operate. I wanted to check if they're right (since i never used any other Linux on the long run) and everybody says that Ubuntu is one of the most stable distributions.

So... right to the point. For the first time since i installed the OS, i decided to use theHarvester and emailharvester and i couldn't install them. It says, that the packages were not found. So i though "Oh okay, i'm an idiot, let's see what it says on the Kali website" and it seems that I'm entering the command correctly to install the software.

Are those tools specific for Kali? Is it normal to not be able to install them on Ubuntu?

Thanks,
- Anthonzie