Well, while I ended up using the autofire button with the normal gun halfway during the run because of the stress with dying on the Snow Field stage, it still felt great to have practiced enough to know how to take on many of the obstacles to finally beat this game for the first time without relying on the 30 Lives granting Konami Code.
I would like to attempt it again without using the autofire even once, though I actually managed to get to Stage 7 with great results without the autofire during the second loop after this run (which I didn't record for this video)...but died there and lost my last continue.
I recorded it with the RANes emulator (which is based off FCEUX) so I actually ended up registering this victory on RetroAchievements (as it granted me the achievement for beating the game without the K-code), and I actually recorded a "movie file" from the entire run (both this and the failed 2nd loop), which is why I could provide this footage here, and can be used to watch this on the same emulator with the same game but the file being quite small.
Quite neat, don't you think?
In any case, I'll be looking forward to attempt another winning run without Autofire in any section (and maybe even achieve the second loop entirely), but at the moment I'll be trying to enjoy the following days until 2022 kicks in.