i work in a mixed KS1 class so see examples of reception / year 1 / year 2 writing - he seems about average for our year 1s I would say, except as others have mentioned, his letter formation and use of capital letters in words (so for example he uses a capital L in film and splash).I wouldn’t spend too much time over the summer worrying about it. Keep him practicing writing where you can - but give him opportunities to write in play, rather than sitting him down and saying ‘now it’s time to practice your writing’.
so maybe set up an opportunity to write out shopping lists, recipes and pretend postcards. Give him chalks to chalk outside, or other mediums like writing and drawing shapes in shaving foam (always a hit). Keep working on fine and gross motor skills so using play doh, colouring in, bead threading etc and bigger things using hands and arms like ball catching, clapping games etc.
oh and keep reading aloud with him - exposure to different texts and vocabulary really helps in his own writing. Check his understanding of new or more tricky words, talk about what they mean and how they are used, he can then draw on these in his own writing.
I've worked in different schools where writing is taught differently - some use cursive formation straight away (so with a lead in and a lead out on separated letters) and some teach like your sons school, without it. I can’t say that either way is ‘better’ to be honest, handwriting ended up mostly ok in both situations. It’s infuriating because joined up legible handwriting is a requirement for year 6, but then as soon as you go to secondary, provided it is readable, no one cares if it’s joined up and ‘correct’.
please don’t worry about your dc’s writing though, he’s not miles off where he should be.