I come from a Samsung Galaxy S20 5G to a Pixel 6a, so I can't really tell about 5a vs 6a...
But in my case, to be honest, from hardware/performance perspective, I think S20 was not worse than the 6a.
I took the 6a because of its size same as the S20, I did not want bigger phone.
I only bought the 6a because of GrapheneOS, it was a big jump for me. I had an interresting offer at 309€...
The interresting thing about Pixel 6 family are the support update for 5 years, but the 5a is still supported, so I guess you can wait for the 7a if there is one.
Graphene's wiki consider 6a really better than 5a in term of performance, but if 5a is running fine for you, you may want to wait. it depends of how much you pay for it today.