Hi Peter,
Greeting of the day!
I have read your requirement. I can be the best solution for you. I have been working in TYPO3 since last 7 years. I have worked in TYPO3 6.2.x, 7.6.X, 8.7.x, 9.5.x, 10.4.x, 11.x.
I have created many Extbase/Fluid custom extension, TER extension exted, HTML to TYPO3 with FLUIDTEMPLATE, mask, gridelements etc.
I have developers in my team as well. So It would be not a problem if you need more developers.
Let's discuss more in chat.
Waiting for your reply!
Best regards
Abdulhafiz Shekh