Unfortunately, I don't think that this is something possible directly in HubSpot because there is no such thing as a "Days left until the close date" property in HubSpot and Custom reports relies on properties, but here are somethings that you could try to create that property.
1- If you know how to code, that would be easy to achieve what you want by creating and updating a "Days left until the close date" deal property using HubSpot APIs:
2- If you don't know how to code, a workaround could be to create "Days left until the close date" contact property and use a "date-centred contact workflow" to update your "Days left until the close date" deal property
Do not hesitate to ask questions about either suggestion.
Unfortunately, I don't think that this is something possible directly in HubSpot because there is no such thing as a "Days left until the close date" property in HubSpot and Custom reports relies on properties, but here are somethings that you could try to create that property.
1- If you know how to code, that would be easy to achieve what you want by creating and updating a "Days left until the close date" deal property using HubSpot APIs:
2- If you don't know how to code, a workaround could be to create "Days left until the close date" contact property and use a "date-centred contact workflow" to update your "Days left until the close date" deal property
Do not hesitate to ask questions about either suggestion.
I guess I am a simpleton here but are you telling me that HubSpot does not have the ability to calcuate differentials in dates and/or add something like Close Date - Now() = Number of Days to Close? I did notice that when I was trying to filter on Contacts using "contains exactly" and I put in 3 characters that are in a piece of text in the column, the result was null. Seems like "like" would be appropriate to have in the filters and calculations.
Your use case seems to be very closely related to sales forecasting to me. At our organisation, we have been using one of the app which integrates with HS. Since we are able to forecast the sales, I believe forecasting the number of days for a deal closure should not be an issue. Sprinkle Data has a machine learning algorithm which empowers the frecasting feature for the tool.