Hi,
I am experience magento developer with 10year+ experience.
I will match your m1 site and m2 site to the extent and make them mirror, I will not do the design task.
I have much experience in magento 1 to magento 2 migration with many site, if you DM me I can share you my past work links.
I have gone thorugh with all your requirement about the magento migration, I will make sure that no product attribute will miss.
I can guarantee that the products, categories, cms pages, orders and all the core data will be migrated to the newer version 2.3.5
Proto theme I will install and setup the new theme customization. Will setup all the required extension to the newer version.