This doesn't necessarily help with finding
new friends, but Minecraft along with various video chat services really helped my 10yo kiddo hang on to his friends during COVID.
I made a point to get contact info for all his friends' parents so we could coordinate. I signed up for whatever voice/video chat app his friends wanted to use. With some friends he had to just use my phone.
I asked him to find out what devices his friends had, researched cross play games, and made a chart with device OS on one axis and cross play games on the other. Then we gave prepaid Steam/Google Play/etc cards to his friends along with copies of the chart so they could play together. They ended up mostly playing Minecraft.
I got both Minecraft Java and Bedrock so he could play with everyone. Seriously, that game, especially when they were able to play on servers like Hypixel, was the most like actually getting together.
His computer desk is in the same room as my worksace, so I ended up spending a lot of time helping him and his friends learn to communicate online, breaking up fights, mediating, making up, assertiveness training, empathy training, etc, etc. I think I was able to help them learn relationship skills that would have been hard to learn without a grown-up who could step in at key moments (and stay away the rest of the time).
It was a lot of work, and my employer was very gracious (my boss was doing the same for his kid).
I wish I had more to say about helping kids make new friends. I wish you and your kiddo all the best! Hang in there!