In rest sharepoint: how to compose the user's display name?

This is a question about rest and sharepoint.
I am fetching the items of a list and one of its column is a people column called SalesManager.
When I run console.log I see the name as two properties:

SalesManager {
      FirstName: John
      LastName: Doe

I know that expanding the SalesManager I can get the First and Lastname like this:

let select: string =
    "SalesManager/FirstName, SalesManager/LastName";
  const items = await sp.web.lists

With that expansion I can set the SalesManager name in the state in this way:

items.forEach(item => {
         item.SalesManager.FirstName + " " + item.SalesManager.LastName

and it renders on the page like John Doe. No problems there.
What I want to do now is filter the result based on the SalesManager’s name (John Doe)
So I did this:
First I fetched the current logged user name:

let currentUser = '';
sp.web.currentUser.get().then(result => {
  currentUser = result.Title;

currentUser has now John Doe.

in the query I tried do this:

let select: string =
    "SalesManager/FirstName, SalesManager/LastName";
  const items = await sp.web.lists
    .filter(`'SalesManager/FirstName' + ' ' + 'SalesManager/LastName eq '${currentUser}'`)

I tried to put together the First and Lastname and then compare it with the currentUser. Obviously it didn’t work. But I think it should be a way to do it.
Do you now how it is done?

I just noted that I wrote the same post twice but I can’t delete them. Sorry for this!!

Best regards

If you want to filter people fields using the current user context, you should always use the email property. As it is unique it won’t cause problems in the future too.

.filter(SalesManager/EMail eq ${currentUserMailID}}

Also to fetch the user’s name from the people field the property name is displayName or Title. But you will definitely get the user’s full name. If you have checked all the properties and still not finding it contact the IT department.

Hope it helps
Thank you