External link instead of subdomain

[chainazo]

On my company website I would like to put a link that leads to an external website (this website is also mine and talks about one of the products I offer).
I understand that the most “correct” thing would be to make a subdomain instead of a totally different web address for that product, but I would prefer it that way.

My question is whether Google would penalize the "original" website for linking to external websites.
I say this because in general on corporate websites I do not remember having seen links to external sites and maybe is a bad practice, weaking my seo. Thank you.

[aristotle]

What is your reason for doing it this way? Is the page on the external domain designed to look like an independent review of the product? With the ultimate goal being an increase in its sales?

[RedBar]

I have several linked standalone websites that have much more in-depth information and images than the main corporate site. These are all keyword widget brand domains and have been established mostly for 20+ years therefore I have no idea whether or not it is deemed "bad practice" these days, my sites are for my customers' education, they are not there to satisfy the whims of some algo wizzard at The Plex on a Friday afternoon.