I have not seen numbers for Kuiper but there are many numbers for Starlink: some announcements, lots of speculation and no two remotely similar. A fairly popular number is 1Gbps for a user terminal. A fairly old number is 17Gbps for a satellite. The other important number that ISPs pretend does not exist is contention ratio. If you have bought 1Gbps the chances are that is shared with 50 other customers (20 others if you found/paid for a quality service). Very often that is fine until everyone is at home watching netflix at the same time because of corona virus.
By all means search for numbers but look out for number of satellites, number of frequency bands, number of spots (a single antenna can send multiple beams in different directions at the same time), bandwidth per spot and how the signal connects to the rest of the internet. Starlink's plan for later is the satellites will communicate directly with each other with lasers. The existing satellites do not have lasers because the lenses could survive re-entry. Without that, the least latency connection is to bounce the data between satellites and ground stations until it reaches a ground station near the destination. Going a long way across the planet by fibre does not eat the bandwidth of multiple satellite but costs more latency because the speed of light in glass is about ⅔ the speed of light in vacuum. There is some utter sillyness from existing ISPs saying Starlink should not qualify for rural broadband subsidies because GEO satellites have 600ms latency - even though Starlink data never goes anywhere near GEO and the latency will likely be less than for fibre.