Is their something like this for NT8 ? They have a bunch for MT4 platform. Would be nice on NT8 so you could put in any symbol and watch a few markets.

Quantum Trading have multiple currency strength & ranking indicators for NT8. They can be purchased in a pack or individually: https://quantumtrading.com/shop/product/currency-heatmap-for-ninjatrader/

For non-FX markets, you might consider something like SI HeatMap Pro from Shark Indicators: https://www.sharkindicators.com/products/heatmap/