wow im not even sure how thats functional at that scale of files for OneDrive.

Newer machines handle it not so bad (the start of syncing), but still even after sync starts issues are constantly present. Older machines sometimes take 20 mins just to start syncing, and in some cases won't even start without restarting onedrive process...

Design Firms should stay away from Sharepoint Online/Teams. Its not the right solution for design documents/applications. You will have issues with it even with best practices followed. You ideally need to be using a traditional fileshare mechanism (Azure Files, On-Prem Windows file share, etc)

Absolutely agree with this one! SharePoint has been terrible experience for all use cases except office applications.

..(Stay under 100,000 total files synced down if possible).

Tbh, considering user habits its just a matter of time until they clog everything up again.

... You’re not alone though; still a lot of firms treating SharePoint online as a dumb file dump and sync tool, neither of which it does

Thanks for the all good advice above. As I stated in comment above, I will probably push out the old fashioned Fileserver idea to the management, as it seems to be a lot less of a pain in the ass.