Bags and cupholder have already been mentioned. It is super annoying to not be able to carry things and move at the same time.

The sportbrella attaches to almost everything.

https://www.amazon.com/dp/B00HA2ZKCO/ref=cm_sw_r_cp_apa_glt_fabc_CQMJMPRD81WFZGP6MG7B

The reacher grabber with the suction cup ends because the others suck. It can reach cans down from high shelves in the grocery store or pick up an egg without breaking it.

https://www.amazon.com/dp/B00O47ILVA/ref=cm_sw_r_cp_apa_glt_fabc_8T3V0XP7AQPARB4P28DK