bike for 7-8 year old - decided to go petrol? any thoughts

[kyrusdemnati]

total newbie
but son is interesting in dirt bikes, i would rather get something future proof rather something off amazon for around £350

ive heard pull start motors arent great
i can pick up 50cc 2 stroke for around £800 uk, i do think thats a bit steep

any suggestions of good bikes?
son wont be on the track anytime soon, just a bit of local fun and if need be will consider in future

thanks