ERPNext Manufacturing Hybrid/Flexible approach?

Hi, I have installed ERPNext on docker in windows 11. So far I am quite impressed by the overall system. Its clean, smooth and is quite flexible.

I am primarily interested in manufacturing. While the module and approach is solid but our approach is a bit different/difficult to implement. If any one could guide me that would be much appreciated.

Our scenario:

We offer OBM & OEM services. We have our branded products and we have customisation and branding for our customers as well.

We have more than 5000 products in our own catalogue plus our customer catalogues. I get that I can make one main product and add variants for those, such as branding, finishes, packaging etc. This would increase the over all items to possibly 20,000+ maybe much more than that.

The main issue arrives in manufacturing. Some processes we do in our own manufacturing unit and some are sub contracted to vendors. To make it more confusing, we may buy the product that has been processed up to either stage 1, stage 2, stage 3, stage 4 etc. We may subcontract the process to different vendors at different stages.

for example we gave raw material to vendor, who completed process 1,2,3 and returned us. We then do process 5,6,7 and then give to another 1 or two vendor to do process 8,9,10 or simultaneously do process 5,6,7 same as us to reduce inhouse workload.

So my question is how can we manage this? how can we track at what stage is the process is it? how can we keep track of the costs that the product has accrued during its production process and subcontracting process?

i have came across solutions that when creating PO, I can select subcontract option and provide raw materials. But for those I would have to create BOMs for each process, e.g. bom-item-process1, bom item-process-1-2 and so on. This increases the over work load, as we would have to possibly create 100K+ boms.

if we just create a vendor PO and mention that process as service cost, how can we track the processes completed for any individual product? I can see we can issue material to vendor for that po, but we have to create additional stock entries. This would not be practical due to large number of products and variants and processes.

Currently we are somewhat managing it in excel sheets, where each process in mentioned in columns for each item, and qty is noted at each step, process 1, process 2 etc till it reaches completion/packaging/dispatch/store etc.

I am looking for a similar approach where we can move the product through different stages/operations and be able to allot related expenses primarily from vendors, and see at which stage is the item at.

is there any solution for this? What would be the approach to tackle this? Any assistance would be greatly appreciated! Thanks.