Hi There!
I’ve used ui-grid before. It doesn’t support accordion-like grouping out of the box, but I’ve seen examples of it being done. On that same note, I know that it won’t be a clear path to create this additional functionality. I do think wiring a bootstrap accordion into your ui-grid might be the easiest path forward, which is why so many people have attempted it. It allows you to focus on the data / logic, while bootstrap does the heavy lifting of css.
If you are looking for a fast win and have a budget to work with, check out ag-grid. Their enterprise version rolls with accordions (called grouping and pivots) out of the box and is probably the most advanced grid for AngularJS that I’ve worked with.
Hope this helps.
PS: AngularJS is old, but it isn’t the stone age yet. It’s staged of end of support around 2021. Until then small fixes will be added occasionally. Our team has used technologies like Webpack, ES6, Babel, and Typescript to spruce up this old framework until we can cross over to Angular.