Bike recommendations for a tallish 7 year old?

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DS needs a new bike and the options out there seem huge compared to the time I bought his previous bike.

he’s grown out of his frog 52 (20” wheels). so needs something bigger that will last a few years. Any suggestions would be appreciated!

To be honest, you probably won't find something that's going to last for a few years at this age. The changes that your DS will go through between 7 and say 10 or 11 will be enormous, both in terms of height and physical abilities and interests. At 7 I would opt for a general purpose hybrid type bike - something like the next size up Frog or the Islabikes Bheinn 24 perhaps - but by the time he is 10 those would seem very babyish and he may well be big enough for an adult bike if he is tall. Plus by then he may have strong feelings about the type of bike he wants and may prefer something more specific like a mountain bike or BMX bike.
I am a kids cycling coach and I would say that Islabikes and Frogs are still the most popular with our club members. They are both brands that hold their value well so you're likely to recoup a lot of the cost if you buy one and sell it on. Or of course you could save a bit of money by buying second hand yourself. Children's bikes at this size seldom get worn out as they are outgrown so quickly so you can often find second hand ones in very good condition.
There are, as you say, more good quality child specific bike brands on the market now though. A few of our members have Woom bikes and I've seen a couple of Squish bikes too and they both look like pretty good brands worth considering.Another very interesting concept is Black Mountain "growing" bikes which can be adjusted to last a growing child longer. I doubt you'd get one that would last a few years from now but might be worth a look.
As a general rule I would say buy the best /lightest bike you can afford as weight makes a big difference even for adult riders but for children the weight of the bike is a bigger percentage of their body weight so it's even more important. A heavy, difficult to manoeuvre bike can be very off putting for a child. Don't be tempted to buy a bike that is too big for him to grow into as if it's too big he won't feel confident and it will be difficult to manoeuvre. At 7 I would go for a straighforward multipurpose bike with a few gears. Personally I am not a fan of suspension on bikes for young children. Suspension forks add significant weight and complexity to the bike and are unnecessary for the typical 7 year old who may not even weigh enough to really use them. So keep it simple, keep it light, pick a reputable brand and you wont go far wrong. It might come down to what your local bike shop stocks in the end as there's quite a lot to be said for having a local supplier.
Or the other thing you might consider is renting from somewhere like the Bike Club where you can swap once a bike is outgrown.
Good luck - hope you find something suitable.

Thank you! That’s really helpful, this was his second Frog (he learned to ride quickly on smaller frog bike at 3 years old and I’m pretty sure it was because the bike was so light that he could ride so young)- they’ve both been great, so tempted to get the next size up Frog