Did you verify their licenses?
What licenses do they have?
Is it a business license and a contractor's license?
Do they have the correct license to install gas appliances?
In Texas, specialty contractors such as plumbers, electricians, and HVAC workers will require a state license, while general contractors will get their license through their local jurisdiction.
If they have a business license, then they can set up an account with local wholesale suppliers and buy Jandy products like heaters.
What is the reason they cannot get the Jandy heater?
To work on gas, the company needs to have the correct license.
LNG License Categories
Any organization that performs any of the Liquefied Natural Gas (LNG) activities described below in Texas is required to be a licensee of the Railroad Commission of Texas.
Category 30. General installers and repairmen. Authorizes the sale, repair, service, and installation of stationary containers and LNG systems.
https://www.rrc.state.tx.us/media/rdxes2sy/onlinedatalookup_plumber-acr.pdf
https://www.rrc.state.tx.us/media/00yebppl/onlinedatalookup_certified.pdf
https://www.rrc.state.tx.us/media/ipmezszg/cat_30.pdf
https://www.rrc.state.tx.us/media/bbclgqcq/lng_licensees.xlsx
Is the person going to get a permit or are they asking you to get a permit?
Are they going to run a new gas line?