Am little confused about some netlify function features

hello all I am working in a project that is deployed to netlify i have a question about netlify function I like to send a email with netlify function I read from the docs that it’s not a problem if i dont install some dependecies in the function folder that the netlify bots can went to the package json in the root of the project from this link and i went to netlify function exemples and see alot of exemples that doesnt work with validation in the function is that a not a problem ?
and i have another question about validation in the function because i do some validation in the front with Yup and when some people disactive javascript i want to add some library like Joi isn’t a problem if i add a lot of packages is that not a problem when netlify deploy my function folder to aws lambda ?

I think you’ll be fine as long as you stay inside these limits: Functions overview | Netlify Docs