Well, it's not the same thing really, you don't have to go to an engineer to get an A rated fuel scoop for instance. What if instead of just buying an A rated fuel scoop you had to unlock an engineer, gather mats and do the engineer game to get an A rated fuel scoop. There are fundamental differences between the two where you can get a fully A rated ship with just credits but you can't get a fully top rated suit with just credit. The equivelant thing in ships would be buying a ship with an A rated pre-engineered FSD. I don't think you can directly compare the two in that way.
But that's just my thoughts.
You wouldn't. You'd just have to upgrade. You can't engineer fuel scoops.
However, if we are talking about engineerable modules, its the same. Its only the upgrade part that is different then. You can't by B and A equivalent stuff. Engineering is engineering.
We can look at it in another way though. Consider Odyssey suits and weapons like being all A rated, or there are no eqivalent A to E grades, but instead we have two types of upgrade: grade upgrade (equivalent to ship module engineering) and engineering (equivalent to applying special effects on engineered modules).
That is perhaps a better way of looking at it, as they do kind of similar logic. Odyssey upgrades increase performance (although there is only 1 path, unlike with ship engineering there are multiple possible paths), whereas special effects on ship modules do the same as Odyssey engineering, give the module some ability it wouldn't have otherwise or modify the stats in an extra way.
So yeah, you can look at it in different ways.
Ultimately it all depends on how easy you want to make things, how much you care about doing Odyssey stuff, and how much time you are willing to invest in upgrading.
Personally it took me a couple of weeks to do my Mav suit to grade 5 and engineer it. That's a one off as i won't ever need to do another one. I did do two Dominator suits because i wanted different engineering effects for the Dual L6 loadout compared to the other loadouts i have (improved jump assist mainly, which i didn't want on my regular combat suit). But those are both done now. I've got 4 weapons fully engineered and more in the pipelines, i'll have those done in a few weeks.
I only started playing Odyssey in October/November, with some breaks, and spent some weeks doing BGS work in between upgrading. Its been a chore, but not a terrible one, and since I enjoy Odyssey missions, simply by focusing on mission rewards that give me what i want, combined with base raids via power restore missions and some bartender trading, I get most of what i need just by doing what I like. I know i'll hit a brick wall on Manufactured Instructions towards the end, but they can be got via missions, sometimes 5 at a time. I have 8 at the moment, by the time i've got the other stuff, i'll probably have at least 20 from grabbing while doing other things (recovery from crash sites, power restore missions), and more from selecting missions when i'm just running missions for rewards. I'll perhaps need to focus on MI mission rewards at the end, perhaps a few of those with 5 MIs as rewards will see me done.
And unlike ships, i'll do very little upgrading/engineering of ground stuff after that. Ships i'm always tinkering with. Ground stuff i'll do for fun and BGS work.