Help: New Laptop but how to swap drives/windows 10

[.:SAmSuNG:.]

Hi all ive been out of the gaming scene for years now and just owned a 13" HP Envy Ultrabook (7th Gen i7 with onboard graphics) but was about time to upgrade. Now I have abit of a dilemma that i could do with some advice on the best way to go about this.

My current drive set up is:

• HP Envy - 1TB Samsung 970 Evo - Windows 10 attached to my Microsoft account.
• Lenovo Legion 5p - 256GB NVME SSD (Not opened to check brand) that will have Win 10 on but not powered on the system yet.
• Spare 256GB WD (I think) NVME SSD that was originally in the HP.

So my goal is to sell the HP with its original 256GB WD NVME SSD and a fresh copy of windows for the new user then swapping out the one in the legion with my 1TB 970.

So desired new set up:

• HP Envy - 256GB WD with licenced fresh install of Win 10 to sell for new owner.
• Lenovo Legion 5p - 1TB Samsung 970 Evo using the Windows 10 that's attached to my Microsoft account (if possible).
• Spare 256GB NVME drive from the Lenovo that I will use in an external SSD caddy.

So I guess my questions are:

1. Do I really need to reinstall windows if I move the Samsung 970 SSD directly from the intel based HP to the Ryzen/Nvidia based Lenovo? Would the windows sysprep tool be ok?
2. How do I go about getting one of the licences for Win 10 onto the HP to sell?
3. What would be the order of operation? The Lenovo has a spare M.2 bay that can be utilised or I have an external SSD caddy.

Hopefully you guys can understand the goal here and offer some advice please. I have not even turned on the Lenovo as fear it might register windows to the device if it hasn't already.

Thannnnks