Shimano come with the fluid in place and yellow plugs on the end of the hose, so you can cut them the right length. Barbs & olives in the package to fit. So you need to trim, fit the barbs/olives and install the levers.
Check the listing carefully. If they’re brand new retail boxed stock then in theory yes, but hose shortening or threading through internal routing is likely to end with a brake that ‘works’ but would be improved by a bleed. Don’t care about all the people claiming you don’t need to bleed after having the lever end off. Most people are going to need to bleed to get full performance after splitting the circuit.
European bargains and other grey stock in plain boxes or bags and I’d bleed as a matter of course regardless. Someone who doesn’t care very much has swapped the levers round for UK in the vast majority of cases.
Agree on needing to bleed if you disconnect the hose. It’ll probably work fine initially, then once the pads wear and the level of fluid in the reservoir drops, the small amount of air you got into the reservoir will start to make it into the brake line and you’ll be complaining about the wandering bite point.