Best routing options at initial domain name

I am finishing this site now.
This site will be made of several sites. A buddypress on the main site. An event/news subsite, a Woocommerce boutique subsite and maybe a project managment subsite later.
I don't want my main buddypress site to be the primary site on which my users are arriving. The primary site needs to be a subsite as well that will route the user to the approriate subsite according to his needs : register, sign in, visit the shop, see the events...
I have tried to get Buddypress defined as a subsite, it worked but I had several issues afterwards, in missings links, images and strange behaviour of maps based plugins.
So I will keep buddypress on main site but need a routing that will allow to initially reach the landing subsite when guests are typing my domain name.
Is it sth that has to be done form the hosting company, dns , etc ?
How do you see it working ?
Any advice / recommandations ?
Best regards,