I looked at your link, that is too big to fit inside the case of the fleshlight. You might use it with the sleeve outside of the case, and the air pressure would be handier in that instance.
I had seen a post several months back about a micro mesh fiber USB heating pad. They were something that was paypal only and they were like $2 each. The fit into the fleshlight case and wrapped around the sleeve and were not too bulky.
I looked at several other heating pads at that time. I liked the looks of some of the neck pads, but I didn't get anything.
Now your going to make me spend hours looking at heating pads on Amazon. :-0
Edit: Ok, you made me look. I found a USB carbon fiber pad, but it was too big.
This one looked like you could do something with it. 5 small pads and $13: https://www.amazon.com/Electric-Heating-Clothes-Outdoor-Camping/dp/B07Y8C6XZ6/ref=sr_1_3?crid=2VH2421TW8JRF&dchild=1&keywords=usb+heating+pads&qid=1600570676&sprefix=USB+heating+pads%2Caps%2C192&sr=8-3
This one is a 2.5" wide and 42" long wrap. (36" of heated pad) and washable! https://www.amazon.com/Sunbeam-Customized-Multiple-Settings-Auto-Off/dp/B07TB5WPYH/ref=psdc_3763871_t2_B075G2DG1D
This one I think I like the best. Its a elbow or knee joint pad. Also washable. Both this and the one before are from Sunbeam. https://www.amazon.com/Sunbeam-Flextemp-Therapy-Settings-Auto-Off/dp/B07T951FL3/ref=pd_bxgy_img_2/163-7903679-7141030?_encoding=UTF8&pd_rd_i=B07T951FL3&pd_rd_r=aa88b195-6a35-4de7-8545-d202557eeec4&pd_rd_w=sWdPD&pd_rd_wg=T5skN&pf_rd_p=ce6c479b-ef53-49a6-845b-bbbf35c28dd3&pf_rd_r=C87WXZSNTHSW50MTHGNE&psc=1&refRID=C87WXZSNTHSW50MTHGNE
this one is a neck heating pad. I think its the smallest of the ones that I looked at. Its also cheaper than the two above. https://www.amazon.com/Comfytemp-Adjustable-Temperature-Electric-Stiffness/dp/B085ZNFM7C/ref=sr_1_16?_encoding=UTF8&c=ts&dchild=1&keywords=Heat+Patches+%26+Wraps&qid=1600573071&sr=8-16&ts_id=3763861
These might work better with an Onahole than with a Fleshlight as the Ona doesnt have a case. I'm wondering about wrapping the fleshlight case with that 2.5" wide one.
Have a nice one.
Mike in CO.
That tiny solar panel isn't going to do much of anything, short of run a tiny LED. That being said, you could probably get 2 or 3 or those usb battery banks, and keep them recharged in the house, and use something like these ( https://www.amazon.com/dp/B07Y8C6XZ6/ref=cm_sw_r_cp_apa_fabc_vsFPFbM4RPJ7J ) to warm the bowl. I use them in my jacket, and they work well enough. Just make sure you tape over them with waterproof tape.
For a more permanent, and hands off option; I use these heat mats for my seedlings ( https://www.amazon.com/dp/B073PTZCJ4/ref=cm_sw_r_cp_apa_fabc_giFPFbD9NRHZ1?psc=1 ) I don't have this tiny one, but I have the bigger ones and they work really well, not to mention The little one only uses 6.5 watts. The big one I think around 18.
With 220 watts of solar panels and a charge controller, ( https://www.amazon.com/dp/B08721N23D/ref=cm_sw_r_cp_apa_fabc_MnFPFb27WK6SX?_encoding=UTF8&psc=1 ) You should be able to keep a 800 - 1000 watt hour battery ( https://www.amazon.com/dp/B07SW353M8/ref=cm_sw_r_cp_apa_fabc_XxFPFbKCC70E4 )(lead acid can only be discharged to 50%) juiced up enough to run the 6.5 watt heater, and inverter, for around 2 days, which is realistically what you would need with winter sun. Also, If you wanted to get fancy you could put a temperature controller ( https://www.amazon.com/dp/B015F4VFGI/ref=cm_sw_r_cp_apa_fabc_DHFPFb4428ZBN?_encoding=UTF8&psc=1 ) on it, that will probably save electricity because you might not need to actually heat it all day. They make one specifically for that heat mat for less than $20. Be sure to insulate the bowl as well, putting it in some kind of small enclosure would be a good idea.
Solar panel kit w/ charge controller - $199 100 ah 12 volt SLA battery -$169 Heating pad -$10 Thermostat control -$18 Edit : inverter -$30 Total = $416