Last year I created a sunny perennial flower bed with the help of advice from a perennial nursery. I’ll check later because I can’t remember them all right now. Personally, I only plant hardy and perennial plants. Some that come to mind spontaneously are: coneflower, sedum, perennial sunflowers, stonecrop, autumn aster. The rest later. Sun-loving and hardy herbs such as sage, marjoram, and thyme also do well. I also included two small bed roses as well as carnations (which reseed themselves all the time, they are not perennial). Pay attention to bee- and insect-friendliness and to well-distributed blooming periods so that you always have flowers somewhere from spring to autumn.
And the serviceberry is definitely a shrub. There are dwarf varieties and the larger ones can also be trained as standard trees or trees. We have a copper serviceberry, which I can only recommend. Absolutely low-maintenance, hardy, long-lived, currently blooming beautifully, edible berries in summer, and a wonderful autumn glow similar to maple in autumn. Wonderful large shrub!