You may start with single, and then, when you need some grouping or counting totals for these groups, it’s very easy to add new linked table - just copy-paste whole product type names column into linked field and add upper-level section(s) via lookup or rollup.

But in your case, depending on “how much”, I think you should create at least 2 tables. Or, if you need no grouping/totals, you can leave single and set product type as single-select. Anyway, later you can change it’s type with existing values and it converts to desired field type.

Hm, this is difficult to answer without an understanding of how you’re going to use the data afterwards

Are you going to be assigning said hardware and materials to various jobs, for example? And then would you want to have view whether said hardware was availalbe, or see inventory counts of the materials and such?

With more information about what you’re trying to do I could try to suggest something