Ah, I definitely could've formatted that better, sorry about that. ^-^ For what it's worth, I'm no expert with blender, I was just rambling a bit. I'll try again, but the tldr is that while it's probably not very good for engineering yet, it has been getting better at it bit by bit. Once you change two settings it's easy now to do what you were talking about and move objects by an inch without needing to calculate and type out decimal values.

The first setting is to switch the Units System between unitless (I think this used to be the only option), metric, and imperial. The dropdown for that is in the Scene tab of the right sidebar (the icon is a cone behind a sphere with a dot above it, it's probably right above a red globe icon), under a folder called Units.

To get to the second setting you need to go to the Edit dropdown at the top of the screen, select Preferences..., pick the Input section from the left sidebar of the window that pops up, and under the Keyboard folder activate the checkbox labelled Default to Advanced Numeric Input. My earlier message wasn't quite accurate, it turns out this setting is more important than I'd thought.

With both of those settings changed, you can select something in your model and press g to grab it, then x, y, or z to move along a particular axis, if you then type 1 blender will move the object one foot along that axis. If instead you type 1" it will handle the conversion and move one inch.

As a bonus, the advanced numeric input also lets you use fractions and do simple math, so if you want to move something by 3/8" along the x axis you can type gx3/8"<enter> or if you want to move something by 1/16" less than 3/4" without bothering with the math, you can type in gx3/4"-1/16"<enter>, though unfortunately it's important to put the quotation mark after both fractions or the one without will be interpreted as that fraction of a foot.

^-^' Hopefully that's a little clearer, like I said at the top it's probably still not the best tool for what it sounds like you want to do with it, but the thing you said was on your wishlist has been added and in my experience it did make blender significantly more useful for designing simple real world objects.