Are there any low-level functions for reading files in elisp?

Question

I am looking for something equivalent to this in Python

f = open('2021-11-10.org')
print(f.readline())

I know you can insert the file-contents into a buffer and do something like this, but that is not what I am interested in. I want a way to read a file one line at a time, without reading the whole file in at once.

I want to try making a generator like this (pseudocode):

(iter-defun open (fname)
  (let ((f (open fname)))
    (while (not (eof f))
      (iter-yield (read-line f)))
    (close f)))

Is there anything like this?