Microsoft Power Automate custom connnector

Hi, has anybody had any luck creating a custom connector for accessing a FreeAgent developer App on Power Automate. I’ll give it a try, but would be great to get feedback from somebody who has already gone this route.

I worked on this a while back but didn’t get much further than proof-of-concept, if I recall correctly. More or less gave up when I realised that there wasn’t any easy way to look up an invoice by its id - a feature request that has, disappointingly, languished for around 11 years - and so I’d have to do a ton of paging instead.