shox100 You're welcome.
shox100 Thanks for the reply! However, it may be that the retailer excludes such modifications in its own terms and conditions. In this respect, I would like to make sure that such modifications are not recognizable / detectable if the stock OS has been restored.
To my knowledge, restoring the original operating system leaves no trace of any modification, I still have my Pixel 4a to prove it and nothing indicates that GOS was installed on it before, just don't tell your retailer, he won't know, since your Pixel fully supports an alternative operating system and you don't lose the warranty, you're not doing anything wrong.
shox100 And thanks for the clarification on ROM, I'm completely new to the topic of custom operating systems for smartphones.
Yes, it's a term often used to refer to an alternative mobile operating system, but it's not actually correct.