Sure, the effective landing page will be your property and you can put it on your server as long as it supports the cms it was made with.
I will recommend that you put it on my server (if I manage the server the maintenance is faster and I will give you a discount for the time saved) but you can contract directly with my provider so you are independent.
I donāt want to bind you to me, but consider that the server is important: if you necessarily want to put the landing page on your server and there are problems in the functioning of the cms any additional hours for solving these problems will be charged to you. However, consider that most hosting services (bad or good) offer good support for Joomla and Wordpress.