Version: v5.x (next)
SVG Overlay

Live Editor
const position = [51.505, -0.09]
const bounds = [
  [51.49, -0.08],
  [51.5, -0.06],
]

render(
  <MapContainer center={position} zoom={13} scrollWheelZoom={false}>
    <TileLayer
      attribution='&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
      url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
    />
    <SVGOverlay attributes={{ stroke: 'red' }} bounds={bounds}>
      <rect x="0" y="0" width="100%" height="100%" fill="blue" />
      <circle r="5" cx="10" cy="10" fill="red" />
      <text x="50%" y="50%" stroke="white">
        text
      </text>
    </SVGOverlay>
  </MapContainer>,
)
Result