Giants Roam Disc 3 @$680 US might work for you. It has a suspension fork that can be locked out and 42 mm tires for a good ride/performance balance, it does have a double chainring though. I too wanted a single chaining but couldn't find what I wanted so ended up with a triple. A double is good because it provides a wide range of gears.
There is no need to upgrade this bike as it is just fine as is for your purposes. Better tires is about the only thing I'd upgrade and even then only if speed is important. I bought a 2018 Giant Sedona 3 years ago and love it. Their quality is 2nd to none, Even their lower priced models.
Buying a really cheap new bike to upgrade is like buying a Chevrolet Trax and trying to get Cadillac performance and luxury. Just ain't going to happen. Far better to a buy good used bike and repairing or modifying it.
Last edited by xroadcharlie; 03-23-21 at 06:50 PM.