I find that Balloon flower (Platycodon) and Willow gentian (Gentiana asclepiadea) are very low maintenance, although they do need occasional water in summer.

I would redirect my focus. Many herbs would fit your criteria (except mints-that spread and Lavender-needs sheering twice a year). Rosemary, Thyme, Echinacea, Yarrow, just to name a few.

Then I would move towards more shrubs. Much more low maintenance then most perennials. Depending on your light situation: Escallonia, Hebe, Mock Orange, Butterfly Bush, Acuba, Kerria, or Sambuca! Much more rewarding then a perennial garden, IMO.

I also think shrubs would fit the bill. I'm trying a dwarf mock orange, Philadelphus dwarf Snowflake, and a couple of Hypericum, kalmianum and frondosum. I also have some somewhat tender ones with fragrant flowers planted by my east-facing concrete porch foundation- Choisya ternata and arizonica, and Gardenia Kleim's hardy. Daphne xtransylvanica Summer Ice is lovely and has blooms for most of the growing season. Hardy Hebes make lovely evergreen mounds and some also bloom.

Here is a link that might be useful: Hypericum kalmianum

East exposures open to the sun are not good for many tender plants as there is too much sun too soon in the morning when plants are frozen, causing cells to burst. Then a shadow falls over them in the afternoon, cooling things down nicely well before nightfall. This probably isn't optimal either. South exposures are what you want for ones that crave heat, if certain kinds are damaged by morning sunshine during frosty periods then west exposures can be used.

Peonies fit the bill. Very low maintenance. Foilage looks good all through the growing season with a little water & no care. Some varieties have stronger stems & look a little better without staking, especially the tree peonies.

I too am trying to save my back so I can stay in my house (and enjoy my garden) well into my old age. I do what I call "in-situ composting" in much of my perennial beds. I have very extensive beds and couldn't see doing a fall cleaning and hauling all the stuff up the hill to the compost bin and then hauling compost back down in the spring. I go out in the fall and cut the stuff back, cut it up and drop on the ground next to where it came from. I use scissors over the course of several weeks and get the job done in a leisurely way.

If it is obviously diseased or mildewed or whatever, I get rid of it.

If it is very bushy or shrubby, I don't normally drop it but haul it out. I wish I had a chipper shredder but I don't.

Leaves from the yard I mow and leave on the grass or I mow and rake into the garden for more mulch.

I have even taken the mower into the garden - for instance over oregano and lady's mantle.