That's right! The functions ST_DWithin and ST_Distance can be used interchangeably in an ON condition. If you're looking for ATMs located within 1000 meters of Nourish Hotel, you can use ST_Dwithin:

SELECT 
  sfh.name, 
  sfa.id,
  ST_Distance(
    ST_Transform(
      sfh.boundaries, 26910),
    ST_Transform(
      sfa.coordinates, 26910)) AS distance
FROM sf_hotels sfh 
JOIN sf_atms sfa
  ON ST_DWithin(
  ST_Transform(sfh.boundaries, 26910),
  ST_Transform(
    sfa.coordinates, 26910), 1000)
WHERE sfh.name = 'Nourish Hotel' 
ORDER BY distance DESC;

Alternatively, you can use ST_Distance to get the same:

SELECT
  sfh.name,
  sfa.id, 
  ST_Distance(
    ST_Transform(
      sfh.boundaries, 26910),
    ST_Transform(
      sfa.coordinates, 26910)) AS distance
FROM sf_hotels sfh 
JOIN sf_atms sfa
ON ST_Distance(
  ST_Transform(
    sfh.boundaries, 26910),
  ST_Transform(
    sfa.coordinates, 26910)) < 1000
WHERE sfh.name = 'Nourish Hotel' 
ORDER BY distance DESC;