First try to switch to a wide range cassette like this one
microshift 11-46. The steeper the hill the slower you have to go and to keep your cadence high at slower speeds you need a larger cog. 11-46 will be a very big step up which should solve your problem.
If you still wanna change the bike and 20mph limit is fine, instead of making the same mistake and going for overpriced hybrid bikes like allant, como, look into emtb offerings like powerfly which come with wide range cassette, clearance for wide tires etc. to ease steep climbs, handle non-smooth terrain and be comfortable.