Amazon links:

O2 concentrator: COXTOD O2 Concentrator, Portable O2 Concentrator 1-5L/Min Adjustable Oxy Machine Use for Home Use, AC 110v Air Purifier https://www.amazon.com/dp/B081ZD66W5/ref=cm_sw_r_cp_api_i_pcQvEbBGV5H89

Pulse oximeter: mibest Silver Dual Color OLED... https://www.amazon.com/dp/B07BNZ2Z41?ref=ppx_pop_mob_ap_share