The only thing that needs to be fixed is the relationship between the stated threat level and the actual threat.
I'm not sure I agree here - low-ranked NPCs can be standing 5m in front of you and consistently miss with any weapon, even when you're standing still. The experience is often like that scene from Robocop 2:
The key here is how the devs quantify experienced. The game already does a good job with the initial three in-ship ranks - exploration, trade and combat - through how it spawns enemies in both random events for interdictions and the NPCs that spawn for mission wrinkles. Right now, the vast majority of the player base for Odyssey -- even experienced FPS players -- are likely in the bottom three mercenary ranks. The only currently effective way to balance combat, therefore, will come through proper threat description and a reliable relationship between that and the actual threat. Indeed, Elite does this quite consistently for space combat - there are three ratings for resource extraction sites and conflict zones, with additional, more challenging, combat instances through the pirate activity and Thargoid USSes. No one would seriously recommend a starter player in a Sidewinder to go to a pirate activity threat 7 USS. In other words, the difficulty of potential combat should be advertised, and it should be consistent. That would allow players who aren't confident in their abilities to make informed choices, just as they can now with ship-to-ship engagements.
NPC combat behaviour - aggression, use of grenades and flanking - was tweaked during the alpha. It can be dialled back. I'd also suggest that more than one training scenario would be helpful. Conflict zone scenarios for all three difficulty levels that any player can access from the training menu would be useful as it would help acclimate players to how the NPCs operate. The actual difficulty at these instances (awful performance making the shooting more difficult notwithstanding) is again pretty consistent.
On the flip side, death on foot costs very little (nothing, actually, outside of mission failure fines, which can be paid off after 10 minutes in a High RES bounty snatching from the police ships.) Failure can be an excellent teacher too, as long as your mind is open to the possibility that you can get better. When there's no penalty for death, it means there's no penalty for practice.