May be more of a convenience store than a supermarket.

Charging station for e-Taxis here. It might be only for charging and not a taxi bay for passengers, though?

Local news article gives the address of the old McDonalds as 57-58: https://oxfordclarion.uk/clarion-weekly-28-march-2025/

"Closed down. McDonald's will relocate to here once construction work had completed"
The place has gone or never existed. A user of Organic Maps application has reported that the POI was visible on the map (see snapshot date below), but was not found on the ground.
OSM snapshot date: 2025-02-13T05:46:10Z
POI name: LEON
POI types: cuisine-burger amenity-fast_food cuisine-sandwich
#organicmaps android

"March–October: 8:30–17:00
November–February: 9:30–16:00"
OSM snapshot date: 2025-02-13T05:46:10Z
POI name: Courtside Café
POI types: amenity-cafe internet_access-wlan
#organicmaps android

node/566845886

Company dissolved Feb 2025
https://find-and-update.company-information.service.gov.uk/company/15898128

I've updated this Holland & Barrett to closed as the website says it is permanently closed. Has something replaced it?

Is this area flooded often enough to be tagged as a wet_meadow?

"Permanently closed"
The place has gone or never existed. A user of Organic Maps application has reported that the POI was visible on the map (see snapshot date below), but was not found on the ground.
OSM snapshot date: 2025-02-13T05:46:10Z
POI name: Tommi's Burger Joint
POI types: cuisine-burger amenity-restaurant
#organicmaps android