Cool idea! Some suggestions:

Use ground sprouted flax seed powder instead to avoid phytate bodies potentially binding with the minerals.
I assume you're using flaxseed oil for omega-3 fatty acids? Use krill oil instead.

Cocoa has the same problem, and is hard to replace in terms of taste. Coconut, avocado, hemp (seeds or oil), acai berries, and nutritional yeast might work in some combination, but can all be prohibitively expensive depending on the intended application.

Adjusting the amount of cocoa should lower the amount of fat intake. For optimal retention of muscle mass, 30-35% of the daily caloric intake should come from protein. If you're worried about gluconeogenesis, I understand, and suggest scaling the ingredients such that you can increase the amount of protein once keto-adapted; hemp seeds have a nice 75-25% fat to protein ratio, and is a complete protein source.

Try stevia leaf powder instead of sucralose to avoid potential adverse effects long term. Maybe xylitol or erythritol if stevia is too expensive.

If you're essaying a final go at inducing ketosis, try doing intermittent fasting (IF) concurrently for increased probability of success. To save time, here's a rough sketch of what that would look like:

If the feeding period was from 12-20:00:

• Day -1: Final day of eating solids.
• Day 0: Transition day. Exercise as much as you can without dying or sacrificing form (whichever comes first), prioritising elevated heart rate over all else. If you're measuring, aim for heart rates above 70% of your maximum capacity for oxygen intake (VO2 max); this should be a good metric for how intense an anaerobic exercise was. High intensity interval training is ideal for this.
• Day 1: Consume between 12:00 and 20:00.
• Day 2: Consume between 12:00 and 20:00 - but wait! You ate from 16:00 to 22:00!
• Day 3: Consume between 14:00 and 20:00.
• Day 4: Consume between 12:00 and 20:00.