$.02 I’d change whatever is going on about your existing system to make it shift better and avoid the cost of a specific 1x setup where narrow wide front ring is used in combo with a wide cassette and 1x specific derailleur. Is it possible your existing rig is simply worn and needs a new chain and cassette?

Btw converting to a 1x isn’t an upgrade. It’s simply converting to a 1x. You can upgrade or downgrade regardless of the number of chainrings. If the bike has 3000 miles and hasn’t been serviced it may simply need some work and the upgrades are a matter of normal servicing and replacing of worn components.