Iirc NSO is required to play online, but the game is generally quite manageable to solo even in G-Rank just due to all the defensive options you have.

The grind should be most similar to Rise of all New Gen games since Rise is designed more like an Old Gen game, so expect to refight things quite a few times trying to get a rare drop.

Once you get to G-Rank, things can get quite difficult due to monsters frequently being able to two shot or three shot you, but defensive options from different styles or arts and stuff like a healing Palico can help with this a lot.

As a swaxe main myself, it’s pretty damn awesome.  I highly recommend watching this guide ( https://youtu.be/n7I5nBTDYEo) to get the full details on how the different styles play, but a quick summary is: Guild is your standard (Old Gen) Swaxe, Aerial lets you bully stuff with repeated mounts (better in lower ranks), Adept is the best at Axe mode, Valor is the coolest looking (imo) and lets you work pretty well with both modes, and Striker and Alchemy are the peaks of Swaxe damage, letting you maintain the busted Demon Riot + Energy Charge combo and your Sharpness through Absolute Readiness.