Which integrations can I connect, and what does each one do?

Two connections carry the product: the bank, through Plaid, so every dollar in and out is real; and Stripe, so an invoice can actually be paid online and paid out to you. The rest are importers — useful, never required. Square brings in sales and customers, read-only (invoicing runs through Stripe). QuickBooks brings history in once — expenses, customers, invoices and payments — then disconnects. Xero does the same with expenses, customers and the payments received on invoices. Google Ads brings campaign spend, clicks, leads and conversions to the Ads page and is included in DeskOps through Ad Integrations. Meta Ads connects from Settings with the read-only ads_read permission; it reads ad accounts and campaign reporting and never edits campaigns. Google Business Profile brings in profile figures and review totals. For other systems, bring history through the universal CSV importer. Historical imports still count; they do not make those systems available as connections.