HI,

I'm not sure I understand your goal as you say "I still want them to check out what I'm selling" & "In that way, they can't add them and then proceed to the checkout"; do you mean you want them to check out/submit the cart without actually seeing  the checkout page?

Perhaps you can check these answers in earlier post: https://www.odoo.com/forum/help-1/how-to-disable-add-to-cart-button-in-e-commerce-product-page-in-odoo-12-158753   

For what it is worth I will share how I am doing it now:  On my website, I want no external users to see the sales prices, because products and prices will for sure change after they checkout to get a quotation, so I want to review product and prices after the checkout always and then send them an updated quotation. I am using ecommerce as quotation tool rather than an actual direct sales platform. 

Therefore I am using a pop-up saying that prices will become known after check-out and I only show prices of 0,00 /example prices in a separate Website Pricelist. For products that are 'easy', the quotation is sent immediately per mail, for others only after sales team review. In my view this is an easy and adequate solution that hardly requires any coding or deviations from Odoo defaults in v14. Which is my primary goal - stick close to what Odoo facilitates without too much customization, make it easy to upgrade every year:-)

 Good luck and hope to see your solution on here soon!