Ok, here’s the final setup. To summarize I have an extension cord plugged into the outlet, then 3 items plugged into the extension cord (Roomba, Litter Box, and Power Strip), then I have the small air purifier plugged into the power strip.

Details: Extension cord plugged into outlet https://www.homedepot.com/p/HDX-15-ft-16-3-Indoor-Outdoor-Extension-Cord-Black-SJTW16315BL/206586942?g_store=2812&source=shoppingads&locale=en-US&&mtc=Shopping-CM-F_D27-G-D27-027_003_EXTCORD_SURG-NA-NA-NA-SMART-2997116-WF-New_Engen_PL3&cm_mmc=Shopping-CM-F_D27-G-D27-027_003_EXTCORD_SURG-NA-NA-NA-SMART-2997116-WF-New_Engen_PL3-71700000082410793-58700006989412242-92700062912530036&gbraid=0AAAAADq61UeR2IwpC73_DZ9QXuR_ocple&gbraid=0AAAAADq61UeR2IwpC73_DZ9QXuR_ocple&gclid=Cj0KCQjw29CRBhCUARIsAOboZbIvUSMr2T5ztmhfyc80xtq2_SoiQ27hD_EYZuCETvsxGIfrVcHvHaUaAstMEALw_wcB&gclsrc=aw.ds

The following 3 items are plugged into the extension cord

Roomba https://www.amazon.com/dp/B08C4LC7TG/ref=cm_sw_r_cp_api_glt_i_FBSHNTC1G8GQRYYH7CXK

Litter Box https://www.amazon.com/dp/B08T9CCP1M/ref=cm_sw_r_awdo_H46AT3HMTWVDNHYYGRK2

Power Strip GE Pro 3-Outlet Power Strip with Surge Protection, 8 Ft Designer Braided Extension Cord, Grounded, Flat Plug, 250 Joules, Warranty, UL Listed, Gray/White, 38433 https://www.amazon.com/dp/B073R2D51S/ref=cm_sw_r_cp_api_glt_i_KZN6835FZW78ARHD4H1W?_encoding=UTF8&psc=1

And finally, the small air purifier is plugged into power strip, attached to side of litter box with double sided tape

Air Purifier https://www.amazon.com/dp/B00OLBR0H0/ref=cm_sw_r_cp_api_glt_i_0DY9P06TB62EJBM751DX?_encoding=UTF8&psc=1