The workflow is actually the exact same for the dev and retail Pockets. Both have an exposed JTAG port, but for the retail Pocket, you just need to remove the "hump" on the lower back. You want to make sure you get an official USB Blaster (https://www.mouser.com/ProductDetail/Terasic-Technologies/P0...), because they negotiate a lower voltage level with the Pocket (someone blew their JTAG port using a cheap one).
For a beginner, the Pocket is definitely easier. With MiSTer, you're building a bunch of other framework code that isn't your own, and that adds a lot of iteration time. I also think the Pocket APIs are more refined, but also more limited. I've already written some info about this - https://www.reddit.com/r/fpgagaming/comments/1318jsr/tamagot...
For a beginner, the Pocket is definitely easier. With MiSTer, you're building a bunch of other framework code that isn't your own, and that adds a lot of iteration time. I also think the Pocket APIs are more refined, but also more limited. I've already written some info about this - https://www.reddit.com/r/fpgagaming/comments/1318jsr/tamagot...