Job Costing would be the feature you are looking for, not currently in Manager but I understand that it is a proposed development. Meanwhile you could just use a Project Card to track those items. Alternatively, check out the tracking codes feature which is for business departments but could possibly be adopted for projects. Manager Cloud
Until the job-costing capability comes online, you might get what you need through a simple trick. Enter a job code in the description of everything you buy for a job (perhaps something simple like SMTH for work at the Smith house and ACME for supplies to paint the ACME Distributing building). Then, after drilling down from the Summary to the Supplies account ledger, do a search for the specific code. Every purchase that has that code anywhere in the transaction record will come up.
A Project Card (stationery Item) is a way of manually recording both billable expenses/time and non-billable expenses/time for a project. This source document can be used to double check your invoicing. .