Definately a thumbs up from me for FS over HT.
Unfortunately good stuff isn't cheap and to fit both need a bit of modification because they both needed the same area on the stay to mount to. Got around this by using the rack mounting bars the wrong way around and permanently removing the rear reflector which i must say I didn't like doing on an expensive item, especially as my diy skills are not to A level std. End result is sturdy enough to carry 4kg in one bag without issue.
https://www.thule.com/en-gb/gb/bike-accessories/rear-bike-racks
https://www.themudhugger.co.uk/
A lot depends on your budget. I already had the bike...
The Thule is about €75 from bike.discount, don't forget to order 2 sides for panniers. I also bought pair of quality Vaude panniers(2x24L) for €75. Thule rack is weight limited to 11kg compared to 25kg racks on most HT racks. Shouldn't issue for commuting.
See my Powerfly 7 HT review(review section) for full mudguards, SKS do 27.5 set. Front will work FS, might be able to make rear work, at €10 cheap enough to try.
Head light that runs off bosch system should be straight forward. Both Bike.discount and bike24 do bosch cables and good range of lights (€20-€300).
I'd fit quality usb chargeable tail light to rack instead of Bosch powered one, no cables to disconnect if removing rack.
Ask shop to enable lights and walk mode (trek disable it) on Bosch system.
Ride quality over rough unsealed tracks is far superior on FS. My climbing speed on CX powered FS is limited by power or 25kmh cutoff, rarely by track surface. On HT track surface quite oftens limits speed, quality suspension post like suntour NCX helps but doesn't compare to FS.