I’ve had the unload flag enabled in about: config for months.

Haven’t used the update yet but there are several related flags to change the appearance of unloaded tabs in there as well.

Tab groups are another thing I hope they push out to standard options. Again, there are some neat flags associated with this in about: config.

I use the release version, not nightly or developer. But you can usually find some future features in there. Some good, some not. YMMV.

As always - Use caution.