Although it has been discontinued in 2018 I have been (happily) using Nuance’s Swype keyboard, because Apple does not offer swipe in my language. Unfortunately Swype finally gave up after updating to iOS 14.5 
Is there any iOS 14.5 compatible swipe keyboard that does not require Full Access?
(And preferably is not from known privacy invaders like Google and Microsoft)
That is not an easy topic. 
First of all, it is a shame that Apple does not offer the functionality in every language yet.
The thing with third party keyboards is that they tend to end up being problematic by design. Full Access sounds terrible, but that’s basically what a software needs when “recording” everything a user is typing and maybe even checking back with servers trying to decipher what a swipe meant in the first place. Yes, it would be nice if everything worked locally, but third party keyboards are limited in the resources they are allowed to use.
The customer base for third party keyboards has dwindled because of security issues, bad reputation and because of the fact that Apple has built in features like swipe in many markets.
A trustworthy swipe keyboard from a third party is quite an undertaking. It either has to be priced in a manner that reflects the effort behind it (for a small market) or it has to harvest data (which of course is the opposite of being trustworthy). And for the user, it is very difficult if not impossible to reliably learn if data is harvested, sold or whatever else…
So, it’s either Full Access with all inherent risks or nothing at all, I think. 
So, it’s either Full Access with all inherent risks or nothing at all, I think.
That was the nice thing about Nuance’s Swype: it offered swipe without Full Access.