How to create a bot for a website?

Question

selenium

I received such an order, requiring to write a program for automatically registering accounts on the site, proxies, cookies and all things, and now more specifically.
I apologize in advance for the possible inaccuracy in writing terms, etc., since I have little experience in this area, I am mainly engaged in web development.

I'm interested in where to dig.
I tried CefSharp in c++, as it turned out, it is not very convenient in the implementation of my task. It is necessary to somehow emulate real keyboard input, probably this can be done somehow by embedding js code into the page, but these are crutches. (Stupid functions like document.getElementById().click() and .value = “name” are indispensable, since you need to call keyDown, keyUp and the like events)

I liked the option using Selenium WebDriver, but it seems to me that the option is not quite suitable, since the browser window that opens will “eat” more resources and create its own temporary files, in addition, a specific browser must be installed on the user's PC

Tell me where to dig ?
I would like something similar between Selenium, its convenience (ease of simulating input and clicks) and CefSharp, the fact that the browser itself can be embedded in the application window.