Your NDAs prohibit emailing a colleague about the e.g. project, or discussing it in a Slack DM with the client, or tracking progress on it in JIRA? You have to do NDA’d work exclusively with local tools or end-to-end encryption? Those are some difficult NDAs!
Oh Lord yes. We have very specific communications channels we're allowed to use about any of our sensitive products, and that's only the unclassified stuff (classified is obviously its own, stricter, beast).
We use inhouse on-premises email, issue tracking, and messaging. Depending on the project, external communication does require E2EE email. Development happens on local hardware and software unless required otherwise by the customer.