Have a look at what this company offers - they seem to have a good range.

https://peta-uk.com/product-category/garden-tools/

Good luck with your quest Goldilocks. Obviously you will have googled it.

There is a great deal about this on the internet I typed in 'gardening with rheumatoid arthritis' and so much came up
3 sites that have some specific help for gardeners with RH such as telescopic trowels, seats and plants that need little attention or watering.
https://www.healthcentral.com/article/yes-you-can-actually-garden-with-ra
www.medprorx.com/the-complete-guide-to-gardening-with-rheumatoid-arthritis/
blog.arthritis.org/living-with-arthritis/helpful-garden-tools/

Good luck dont forget this is a form of exercise and it is still important to do a warm up routine before you start so as to limit damage to yourself.

Its important not to get too cold. One trick is to wear 'Silver' gloves/socks (got from the Raynards Society site) they are thin but keep hands warm, they come fingerless too.