Nah, D1 is in a different league.[1] One key feature of D1 is having free read replicas around the globe. That's CF's DNA and I expect this to happen this or latest Q1/24, and again, for free (so, without any surcharge). Re storage: You get ofc more than 1GB on the paid plan.
Neon doesn't have read replicas and even if they already work on it, I wouldn't expect it before 2025 if at all and never at CF's pricing (Neon still charges for egress).
[1] I would compare D1 rather to Turso or LiteFS from Fly or PlanetScale with many read-replicas
This is true. Neon however offers bottomless storage and D1 is 100Mb currently going to 1Gb.