I am unaware of your budget but many riders like ergonomic gel grips similar to this:
https://ergonbike.shop/collections/comfort-touring-fitness/products/gp1-evo-single-twistshift
Front suspension can help. There are suspension stems, if you don't want to replace the fork. If you are interested in suspension forks, 40mm of travel is tiny but nice, however 80-100mm is better suited to your riding. Suntour XC is very good value for the money and very durable.
There are suspension seats, suspension seat posts, you want adjustable preload. Adjusting spring rate requires rebuilding the suspension seatpost/fork. Cycling about and other Bicycle touring based coverage is a good source of info for comfort components. Gotta stay comfy when your ride 8-10 hours a day!