Should I make a *small* computer upgrade? Worth it?

A GT1030 uses about the same power as a GT710/730 series of cards, so it should be fine.

Your weakness is the CPU at this point....

A 300w power supply will work with the following Graphics cards.

GT 1030

GTX 750ti

GTX 1050

GTX 1050ti

GTX 1650

For the most part these cards have No 6-pin power connector and they will work with a 300w power supply, but look out for the oddball cards that have a 6-pin power connector.

Don't buy any knockoff card off ebay. Stick to name brands like EVGA, PNY, Zotac, MSI, Asus, Palit, and Gigabyte. If the price is too good to be true then it's not Genuine.

It's difficult to recommend the GT 1030 because the Integrated Graphics that Come with a Ryzen 5 2400g and 3400g processor are on Par with the GT 1030.

The problem is the AMD A-Series APU's and their FX counterparts suffer from using a terrible and outdated CPU architecture. Your A4-7300 might be advertised as a dual-core but it performs more like a singe Core Intel CPU with Hyperthreading.

Alternatives

You can look at buying a used Intel Socket 1155 or 1150 motherboard that was pulled from a Dell, HP, or an aftermarket brand. These will work with your DDR3 memory. A socket 1155 Core i5 CPU like the Core i5-2400 or Core i5-3470 are $20-25 on ebay. A socket 1150 CPU like the Core i5-4570 will be a little more expensive because it's newer. A socket 1155 Core i7 CPU can also be found at a reasonable price.

You can look at a Ryzen 5 2400g or 3400g, an AMD b450 mATX sized motherboard, and a 16gb kit of DDR4 RAM. You will need to wipe the hard drive and reinstall the OS if you go this route. You can use Windows 10 for free but you'll have to deal with the watermark. Otherwise you can obtain a Windows 10 product key for a low price if you know where to look.