The sample repo is at least well-commented. I've taken the liberty of pasting some of the sample code here, sans comments, so we can see what the code style is like. My editorial take: no thanks. This looks less declarative than jQuery. If this is the alternative, then yeah, you still probably need React (or Vue/Svelte/Astro/whatever)

    namespace App {
      export class SegmentedButtonComponent {
        readonly head
    
        constructor(...segments: ((element: HTMLElement) => Raw.Param)[]) {
          this.head = raw.div(
            raw.css(
              "> *", {
                display: "inline-block",
                padding: "1em",
                borderRadius: "5px",
                userSelect: "none",
                webkitUserSelect: "none",
                cursor: "default",
              },
              "> .active", {
                backgroundColor: "hsl(215, 100%, 50%)",
                color: "white",
              },
            ),
            () => {
              const buttons: HTMLElement[] = []
    
              for (const fn of segments) {
                const button = raw.div()
    
                raw.get(button)(
                  raw.on("click", () => this.select(button)),
                  fn(button),
                )
    
                buttons.push(button)
              }
    
              return buttons
            },
          )
        }
    
        select(childElement: HTMLElement) {
          toggleClass(childElement, "active")
        }
      }
    
      function toggleClass(child: Element, cls: string) {
        Array.from(child.parentElement!.children).map(e => e.classList.toggle(cls, e === child))
      }
    }