How to use JQuery on the new CommerceSDK

[RethaLam]

I am moving our custom from RetailSDK to CommerceSDK.
We make use of JQuery in one of the TypeScript files. We added the file "jquery-3.3.1.slim.min.js" to a Libraries folder under the POSExtension, no nuget packages, nothing. That was the only file needed.
In the HTML-file we were able to just add a script in the header to point its source to the file in the Libraries folder.
The TypeScript file doesn't reference the file in the Libraries directory at all.
RetailSDK is on TypeScript 2.2.2

For CommerceSDK I have to use TypeScript 4.4.4.
Should I use the steps used for KnockOut in document https://learn.microsoft.com/en-us/dynamics365/commerce/dev-itpro/pos-extension/knockout-pos-extension ?
No extra steps other than adding the file under a Libraries folder were necessary for RetailSDK.
Also, nothing was needed for TypeScript to recognize JQuery and $.
For CommerceSDK I get the error that it can't find the name 'JQuery' and for the $-sign, I get the error : Cannot find name '$'. Do you need to install type definitions for jQuery? Try npm i --save-dev @types/jquery
Why would RetailSDK recognize it and not CommerceSDK?
Even after adding the nuget package jQuery (3.7.0), I still get the above errors?