I was almost tempted into buying an all-in-one unit that washes and dries. Only a few brands are releasing these heat-pump based models currently and it doesn't seem quite ready for mainstream release. But the LG model I found did have the ability to preload it with detergent and run up to 60 cycles before filling again. I almost bought it just for that feature. But went with the older more reliable model instead. Maybe in 10 years after this washing machine dies the feature will be more prevalent and reliable.

https://www.lg.com/us/washcombo-all-in-one

I think long term, having two "all-in-one" combo washer and driers would make way more sense than separate washing and drying units. But the price for functionality just isn't there yet.

Both the LG and GE heat pump all-in-one units come with auto detergent dispensers. For the life of me I can't imagine wanting one more thing to break, especially on an LG product as LG is notoriously poor with parts availability.