External sharing strategies for B2B customers / partners

I don't find much information – I apologize if I missed it, but I just wanted to get some feedback and best practices.

We use O365 – MS Teams (for internal purposes only) / Sharepoint (classic websites) for document sharing for external customer partners. A gap between our inside and outside.

Internally – we have set up ORG MS teams (finance, quality assurance etc.) AND we have set up customer / partner-specific MS teams for customer and partner project data.

Externally – we have configured classic sites for guest access – the customer gets access to the corresponding external customer site and document library. (Websites are mirrored by internal MS teams)

This appeared to be a clean, simple configuration that is relatively easy to manage and ensures a separation between internal and external locations to avoid confusion for PMs and engineers as we have had issues with incorrect documents going to customers in the past – this fixed that.

When a document needs to be shared with a customer / partner, we have an O365 management group that approves the document and manually moves it to the customer location where it is available for customer access. Only certain internal users are granted access to the external websites.
Management isn't too excited about having to move and manage documents between two locations.
You would prefer to have a folder in the internal team document library and have it mirrored to the customer location. This can be done via PowerAutomate.

I think about it, but I would rather leave it as it is so that it is regularly checked and checked manually and does not rely on a script / power machine to stay up to date, to clean up and to check regularly. Keep an eye on what is going on with the customer / partner.
I have no intention of integrating and managing external guest users in our internal MS teams. I like the clear separation.

I am aware that these situations and details depend on the needs and requirements of the company, BUT what do other companies do as a strategy for external exchange? We don't necessarily have a problem, we shouldn't have to buy more products, we just want to see what other companies are doing to manage external approval.