For what it's worth, my hiking map solution:
I use Mapyx (OS 1:25k sometimes discount whole of UK to £120) on PC. Software is a bit quirky but my end result is better than Memory Map (who screwed me once too often).
I print out the walk area & route on laser printer (ink doesn't run if it gets damp), carry in a loose-leaf plastic folder-page so I have my route on one or two sheets of A4 folded in a back pocket, very light/compact. I often print a blown up image so it's easier to see detail & read the small print.
Lamination is relatively expensive, can still suffer water penetration, doesn't fold well. May be OK if you repeat the same routes a lot but I don't.
As back up I have the route on a basic GPS (no mapping) and I turn on track recording so if I vary the route I have a record.
The main value of the GPS is getting a grid reference. It has advantages over mobile phone: waterproof, 18 hour AA battery life, better satellite reception, attached with a lanyard, more robust.
I carry, but almost never use, the relevant OS 1:50k full sheet of the area - that's like carrying a basic first aid kit: hope never to need it but stupid not to have one. Similarly, always carry a compass.
For planning purposes Google maps satellite view can reveal paths (especially on open access land) not shown on OS or clarify some tricky navigation areas (e.g. around farm buildings, where field walls have been removed). Street view can be useful when planning a route which might involve a stretch of public road, possibly to preview where the footpath leaves the road and to check how safe the road might be for hikers (busy, no verge and tight bends - best avoided). Also if you need to go through a housing estate, satellite and/or street view can help pin-point features like alleyways between houses.
I tried mobile phone for rural route finding. Dismal battery life (GPS and the phone continually searching for rural network connection seem to gobble power), need to pre-load walk area (as likely no signal), in grim weather had to keep it inside my clothing and it got condensation inside the screen.
How fortunate we are in UK to have such high quality rural mapping.