You might be able to eliminate LibreOffice since you already use the Proton suite which includes Proton Docs. I haven’t used it myself but after creating a new document, it looks like it’s based on .docx rather than .odt. I’m unsure if it’s as mature as the Google suite which I believe allows you to open .odt or convert it to .docx, but if you had some free time you could check it out.
The only other way I’d try to further consolidate workflows is by using well integrated self-hosted solutions, such as Nextcloud and the various apps which integrate with it. But that might be needlessly expensive to set up for a small business as you’d incur the burden of maintaining reliability and security.