Forum Discussion
Small company (8 people) - SharePoint Online Teamsites, Groups or both?
Given your requirements, you could perhaps think to create a single Team (and hence a single Group, with a single team site, and with a single doclib), and several channels inside it (and hence several separated subfolders in the doclib), one for each "department".
IMHO it's a very, very, simple but effective architecture for very small customers, if there is no need for more elaborated permissions. I have adopted such model for several small customers with good results.
IMHO, the good thing about the "single Team / multiple channels" approach that I suggested, is that you automatically get something similar to "subgroups", i.e. a chat space for each channel, a subfolder for each channel, a notebook section for each channel, an email address for each channel etc.
What remains unique, roughly speaking, is the Group modern team site (which can be used as a company-wide site), the Group conversation mailbox (which can be used, say, for emails to/from customers) and, first and foremost, the Group permissions. I've seen in practice that, if you can live with such limitations, this approach could work for very small companies.
Just my two cents...