In case you didn’t know, you can turn off promotional emails in Settings -> Dashboard -> Email Subscriptions or by adding a mail filter to push them all into an advertisement folder, and the other ads can be mitigated by hitting “don’t show this offer again” on each one
My big two are long form chemistry videos (codyslab, nilered) and old archived hours of the first version of the AI show Nothing Forever. Very easy listening IMO and should hit most of your bases. Maybe also look for podcasts on a topic you like, those can be hours long