Forgive me if this idea won't work because of in-game lore or mechanically (or even exists in some form) as I've only been able to sink a few hours into the game so far.
When your custom made main player dies, like literally dies with zero chance of ever coming back, providing you have other party members alive, rather than being forced to reload and do the entire encounter again you can finish up and then finish the day and get to camp or long rest. At this point a mysterious stranger appears and offers to join your party. When accepted you're brought to the customise character screen and can create a new character to continue playing.
Well a continuous playthrough, living with every good and bad decision you put your party through, would be very complimentary to this games storytelling and playstyle as your first made character doesn't seem to be the undefeatable protagonist hero like in typical other games. It also means that should you want to create or test out a new character, you can whilst still experiencing everything for the first time. Rather than having to restart and knowing what each interaction will result in from previous attempts.
The idea can have many variations imposed upon it and here are some examples.
You must convince the mysterious figure to join you through various dialogue options or gold.
The mysterious characters level starts off at a lower level than the rest of your group.
The mysterious character is already an unswappable race and/or sex.
You must find a rare magic item or horn that should "only be used in times of dire need" which then summons the mysterious figure
You get the just. There are endless variations that could alter how and why this interaction would happen and take place and I'm sure there are much more creative minds than mine that can think up more imaginative variations on the principal idea.