I Know that is possible but it is very, very clumsy to have to do that, by the time you have added on the checked bag and seat selection the price can jump 25%, and not all fares are offered though airline websites.
Trying out Kayak it is possible to exclude non-airline website fares which solves part of the problem, then on Kayak you can also select for checked bags but that is not perfect because all they do is add on the fee for a checked bag onto the basic economy ticket so you can still have a non-voucherable fare. At least on Kayak they print under the fare on the main list screen whether the ticket is basic economy or economy lite so you can skip those visually on the list.
Frankly giving up on Google/flights as not able to meet my needs, any other suggestions would be helpful. There's been a proliferation of sub-economy tickets and Google/flights has not been keeping up with this. Also Lufthansa, really, you offer 2 fares in sub-economy: basic economy and economy lite? Who benefits from that nonsense, and 50 points to whoever can name which of those 2 tickets is the higher class, just from the name?
I don't think an option to list ONLY full economy fares is unreasonable.
Edit: Skyscanner doesn't meet my needs, either.
Edit 2: Well, the name of the article was so promising, too bad it doesn't work
https://maphappy.org/heres-how-to-filter-out-basic-economy-fares-in-google-flights/