Preamps and amp heads question

You need to go to a musical instrument website, home audio is a totally different animal. 

Henlo there! I've always used a small combo amp (MG30FX) and all i need to care about is the order of the pedals. I've been thinking about upgrading to a half stack amp.

What I know about it is that you need a preamp to connect to a power amp and then to the cabinet

If im not wrong an amp head is basically a preamp+power amp as a single unit and you connect it to the cabinet

While browsing solid state preamps I noticed that a lot of them look like pedals and I dont really know what they really are (for example a seymour duncan palladium gain stage WH, it appears on the store as pedal and as a preamp but searching reviews on YT they all say its a pedal)

Mi idea of a preamp is something like a mesa boogie but seeing this pedal like thing got me like wtf https://100001.onl/ https://1921681254.mx/

Same thing happens with head amps, im seeing pedal like forms.

Is a pedal style preamp/head worth it?

Any information is welcome!

I got this,..