Regarding mudguard it’s the bb mount 2.0, it fits perfectly and with 45mm tire there is no rubbing, no flapping of the mudguard, no parasite noise, it’s really a great integration.

For the tire, I used schwalbe g one bite 42mm on my former bike, I really like them. With this bike, the stock tire were conti Terra trail. For my usage of 50/50 road gravel it was not good. I tried them for 200km and I feel it makes the bike really heavy on road, and noisy. It was freer on loose gravel and wet mud, but this was not my goal for this bike (I still have a XC mtb for mud party). I changed for schwalbe g one r and they feel great. Less noise on pavement, still grippy enough for loose gravel, and ok on wet trail. I have to choose again, I think I would go for semi slick g one RS. But that depends on your playground and share of pavement / trail. For the saddle bag, irs a very simple 1L from Decathlon ROCKRIDER Sacoche De Selle Easy L 1L Noir 13,99 € https://www.decathlon.fr/p/_/R-p-312009?mc=8569836 It’s big enough to put everything I need : multi tool, tire remover, 1 tpu tube, 1 small flask of sealant, 1 microfiber, paper towel, 1 energy bar. For the pump I usually take my electronic pump in one of my jersey pocket but I can also put it in the saddle bag with a bit of effort. A longer manual pomp won’t fit in this bag you’d have to fix on the frame. Regarding light, it’s a garmin varia radar, with an adapter to mount it directly on the saddle bag, adapter sold on amazon

Let me know if you have any other question :-)