@briljander I have managed to get all of these things setup with three external third parties.
For automatically generating purchase orders, seeing purchase suggestions and complete sales history of every SKU we use Inventory Planner https://inventory-planner.com
For receiving goods you can either receive them off the purchase order, or do what we do and scan the goods in using the module we use for our POS https://www.pos-tpv.com. This also print barcodes with prices which we stick on the goods - useful for instore and for picking orders so you pick the right code.
For picklists and despatch we use Mintsoft https://www.mintsoft.co.uk. They integrate with all the couriers so we print all orders from there, pick, scan the barcode on the order, scan the product barcodes (which checks the correct item has been picked) and it automatically prints the correct shipping label (works out which courier it should go depending on size/weight/cost) and despatches the order. The whole packing process now takes seconds. We've doubled the number of parcels a person can pack in a day.
OK, so all this costs a few hundred dollars a month but any business who is at the stage of requiring all these features will surely easily get this back in a day or two through the increased productivity, perfect stock levels and all the reporting.
It took a while to find all these solutions and it's a shame some of them aren't part of PS/TB, but now we have them I wouldn't even think about going back. They've revolutionised our business.