I've also used PCBway for full PCBA with some customer supplied parts and some PCBway supplied parts and they always communicate well.
I don't think they're the cheapest option, but sometimes you want reliable/reduced-risk more than you want cheap.
Make sure you check what price they are charging for parts on the BOM vs what the parts actually cost and look for any crazy abnormalities like 40% higher. Note that pcbway have to pay china import tax on parts they order from outside china, so don't expect to get the same price as digikey if pcbway have to import the parts for you.
Other parts they don't have to import are often a bit cheaper than Digikey, so you do gain in other areas.
If the BOM cost higher than say 25% of digikey price ask them for a better price. Some parts they will be able to give you a better price if you ask nicely for it. (PCBWay bom price is negotiable). But some parts the price may still be quite high and it will be cheaper for you to order that part yourself and ship to china, paying the china import tax yourself, it's around 13% + DHL fees.
If shipping parts into china I recommend shipping fully duty paid by you, otherwise PCBway will have to charge you again for the duty they need to pay to accept the goods and will probably add a bit extra for their time/hassle. So it's easier to just pre-pay china import tax as part of your DHL shipment. Who pays the tax is one of the options when you make a DHL booking, it defaults them them paying so you have to change it to you. The cost then gets adding to your DHL account a few days after your ship the item.